Report finds that the agency spent millions on training videos and employee conferences between 2010 and 2012. NBC News' Steve Handelsman reports.

The now infamous 2010 Internal Revenue Service conference in California — where goofy, expensive video parodies were shown — also featured $135,000 in spending on outside speakers like a "happiness expert" and a session titled "Leadership Through Art," congressional sources briefed on an upcoming inspector general's report told NBC News Monday night.

The IRS hired 15 speakers to present at the conference in Anaheim, Calif., including $11,430 for positive psychology guru Shawn Achor — referred to as a "happiness expert" by the sources — to lead a 90-minute workshop and $17,000 for artist Erik Wahl to hold a session that used painting as a learning tool, said those familiar with the report.

During his presentation, Wahl painted a portraits of Michael Jordan, Abraham Lincoln, Bono, and the Statue of Liberty, according to the sources. Wahl also lists the National Security Agency and U.S. Chamber of Commerce as clients on his website.

Two of these paintings were given away to conference attendees, at least one of the paintings was auctioned to benefit the Combined Federal Campaign, and one was lost, according the report by the U.S. Treasury Inspector General for Tax Administration (TIGTA), the sources said.

In addition to that, tens of thousands of dollars were spent so that IRS employees could also hear from an "innovation expert" and a "diversity and inclusion expert."

One of the speakers received a $25,000 fee in addition to a $2,500 first-class airline ticket to fly the speaker to the conference, according to the report.

The contracts for the presenters were awarded as sole source contracts, meaning no competition occurred, and taxpayers cannot be assured to have received the best price for the speakers.

Sources told NBC News that the conference was approved by two of the agency's deputy commissioners: Mark Ernst, who left the IRS in 2010, and Steve Miller, now the resigned former acting commissioner.

The revelations were made as part of the Treasury Department's Inspector General's report on IRS spending for travel and conference that will be released Tuesday afternoon.

According to the report, the IRS spent nearly $50 million on at least 220 conferences for employees between 2010 and 2012.

A particular focus of the investigation was the Anaheim conference, which cost taxpayers $4 million, a statement by the House Oversight and Government Reform Committee said.

The IRS failed to adhere to the standard government practice of negotiating lower room rates, and gave the 2,600 attendees perks like baseball tickets and stays in presidential suites, according to the congressional committee.

On Friday, another video was released showing about a dozen IRS employees practicing the "Cupid Shuffle" dance. That recording was produced to be shown at the end of the 2010 conference, and comes on the heels of two other wacky training videos that surfaced in March, parodying "Gilligan's Island" and "Star Trek."

Combined, the total cost of the video parodies was more $60,000, the agency said.

The forthcoming report will outline lavish spending comes at the same time the IRS is being scrutinized for targeting conservative groups applying for tax-exempt status and as government agencies, and as other government agencies struggle to cut spending in the wake of Washington budget battles.

Danny Werfel, the new acting commissioner of the IRS, released a statement Friday calling the conference "an unfortunate vestige from a prior era."

Werfel made his first appearance in front of Congress on Monday to address the agency's targeting of conservative groups. He told lawmakers, "My primary mission is to restore that trust.”

Related: New IRS chief says restoring trust is his 'primary mission'