Donald Trump is fighting back against the public embarrassment his now-defunct Trump University real estate seminar series has caused him, releasing a video featuring three testimonials from former students.

The billionaire Republican presidential candidate has been fixated on a class-action lawsuit filed by other former participants, publicly hammering the judge in the case as a 'hater' who won't give him a fair shake.

No evidence of misconduct has been lodged against federal judge Gonzalo Curiel, who is overseeing the case in San Diego, but the plaintiffs' attorneys who brought the lawsuit may not be disinterested parties.

Robbins Geller Rudman & Dowd, the law firm representing a group of the Trump project's former students, has paid Bill and Hillary Clinton $900,000 for speeches since 2009.

The Clintons earned speaking fees from five law firms in recent years, with Robbins Geller paying them the most.

Donald Trump continues to insist a class-action lawsuit challenging his 'Trump University' business seminars is without merit, releasing a campaign video featuring three testimonials from former students

Robbins Geller Rudman & Dowd, the law firm representing a group of the Trump project's former students, has paid Bill and Hillary Clinton $900,000 for speeches since 2009, according to a Washington Post database

Trump clobbered Gonzalo Curiel, the judge in the case, on Friday before 20,000 fans in San Diego, the city where the lawsuit is being heard

The firm paid Hillary Clinton, Trump's likely opponent in the November general election, $225,000 for a speech in September 2014, when buzz about her likely presidential candidacy had already reached a fever pitch through high-spending efforts from the 'Ready For Hillary' political action committee.

LawNewz.com, a crime and law website that shares ownership with Mediaite, first reported the payments. It pulled numbers from data compiled by the Washington Post and interviewed a New York University law professor who said they didn't violate legal ethics guidelines.

A spokeswoman for the law firm did not respond to a request for comment on Wednesday.

The video, posted on the Trump campaign's YouTube channel, includes praise from Kent Moyer, Casey Hoban and Michelle Gunn, a trio of businesspeople who paid thousands of dollars to hear Trump-sanctioned lecturers teach them how to make money in real estate.

Their voices augment stories on a Trump website –98percentapproval.com – launched in February to push back against a separate legal action backed by New York Attorney General Eric Schneiderman.

Critics have noted court filings that spell out how 32 per cent of paying students were ultimately issued refunds, suggesting that the 98 percent satisfaction rate refers to those who completed the course.

'The courses that I took were outstanding,' Kent Moyer says in the new video. 'They were excellent in terms of the quality of the content. In fact I still have them on my iTunes and on my cellphone, and listen to them every once in a while.'

The self-described business coach's website testimonials include a claim from one unnamed security company owner that he is 'the Donald trump of security,' and a Trumpian reminder from another that 'Kent graduated from the best business school in the world, Wharton.'

A group of former Trump University students claims they were scammed, but the lead plaintiff withdrew from the case after past statements were uncovered in which she praised the program

Trump partisan Kent Moyer says in the new video that he liked the Trump University course so much that he keeps audio of the lectures on his cellphone

Casey Hoban says on-camera that he wouldn't have been able to close a series of Florida and South Carolina real estate deals 'without learning Donald Trump's business techniques and real estate strategies. And I learned them all from Trump University.'

He recalls being offered a get-out-of-class-free card – and a refund – if he decided the course wasn't up his alley.

'They told us, "If you feel you're over your head, or you feel you're not going to use these techniques, and leave your books on the shelf, check out of the class now and we'll refund you",' he says.

Some of the federal lawsuit plaintiffs say they were denied refunds because they failed to ask for them in the course's first 72 hours.

Like the other two testimonial-givers, Hoban is no longer buying and selling real estate, according to the right-wing RedState blog, whose ownership has long opposed Trump on the grounds that he is not 'conservative' enough.

Judge Gonzalo Curiel responded to a 12-minute Trump tirade against him by unsealing hundreds of pages of documents in the Trump University case, a move that enraged the billionaire Republican candidate

Hoban's current business, the Trimino line of protein-infused bottled water, is sold in the basement cafe at Trump Tower in New York City.

Michelle Gunn recalls earning enough from her first deal to cover her Trump University fees.

And in contrast to the lawsuit plaintiffs' claims, she insists she 'never felt pressured to do anything that we didn't want to do. We never felt pressured to go in a direction we didn't want to go, sign anything we didn't want to sign, pay for anything we didn't want to pay for.'

The federal lawsuit itself winds on, with Judge Curiel making headlines this week for unsealing hundreds of pages of documents including sales manuals used by Trump University.

After reporters made hay over what some described as pressure tactics spelled out in the documents, Curiel amended his order to re-seal some of the material – a move that enraged Trump, one inside source told DailyMail.com.

Also included in the documents was an under-oath account from a former Trump University instructor who described the venture as 'a fraudulent scheme' and said it 'preyed upon the elderly and uneducated to separate them from their money.'

Hillary Clinton criticized Trump on Wednesday during a campaign stop in Newark, New Jersey, calling the seminars a 'scam.'

'His own employees testified that Trump U – you can't make this up – that Trump U was a fraudulent scheme where Donald Trump enriched himself at the expense of hardworking people,' she said.

'Trump and his employees took advantage of vulnerable Americans, encouraging them to max out their credit cards, empty their retirement savings, destroy their financial futures, all while making promises they knew were false from the beginning. This is just more evidence that Donald Trump himself is a fraud.'

Trump railed against Judge Curiel during a San Diego rally last week, just blocks from the federal courthouse where he hears cases.

Hillary Clinton chastized Trump as a scam artist on Wednesday during a campaign stop in New Jersey

Michelle Gunn, another pro-Trump former student, insists that she was never pressured to spend money on the pricey real estate seminars

Casey Hoban also praised the Trump University program – although he now sells protein water, not real estate

'There should be no trial. This should have been dismissed on summary judgment easily,' Trump told a crowd estimated at 20,000.

'Everybody says it, but I have a judge who is a hater of Donald Trump, a hater. He’s a hater. His name is Gonzalo Curiel.'

'We're in front of a very hostile judge,' he claimed. 'The judge was appointed by Barack Obama!'

Trump also called the Indiana-born Curiel a 'Mexican,' quickly adding that 'I think that's fine.'

Curiel's order to unseal the Trump lawsuit documents came just hours later

'Defendant became the front-runner for the Republican nomination in the 2016 presidential race, and has placed the integrity of these court proceedings at issue,' the judge wrote in his order.

Trump has said he might make a motion requesting that Curiel recuse himself.

Among the jurist's myriad sins, Trump has said, is allowing the lawsuit's lead plaintiff, yoga instructor Tarla Makaeff, to withdraw from the case this past spring.

That move has hampered Trump's case, which considered her a 'critical' but compromised witness since she once praised the Trump University program on video.

'The reason they want her out of the case is she is a horrible, horrible witness,' Trump told a crowd of a few thousand in Little Rock Arkansas during a February rally held between the Iowa caucuses and the New Hampshire primary.

'She’s got in writing that she loves it. ... Why would I give her money? Probably should have settled it, but I just can’t do that. Mentally I can’t do it. I’d rather spend a lot more money and fight it.'

The Trump campaign released a statement late on Wednesday about Curiel's action.

'The Court's order unsealing documents has no bearing on the merits of Trump University's case,' the statement reads.