Royal Barnes uploaded YouTube clips that hailed attack as 'brillliant day'; he also admitted inciting murder during Old Bailey hearing

A British Muslim who associated with one of Fusilier Lee Rigby's murderers today pleaded guilty to posting videos on YouTube glorifying the killing.

Royal Barnes, 23, of Hackney, east London, and his wife, Rebekah Dawson, 22, recorded and uploaded three videos shortly after the murder in Woolwich, south London, in May 2013.

In one of the videos posted under his account, Musa Real Talks, Barnes hailed the murder as a "brilliant day". In a follow-up, he mocked the outpouring of public grief, laughing uncontrollably as he drove past floral tributes.

On Facebook, Barnes, who knew one of the murderers, Michael Adebowale, also posted the offer of a reward for avenging the rape of an Iraqi woman. None of his 500 friends replied.

The post, on 12 June, 2013, stated: "Any1 who kills an invading soldier in Muslim land I will give them a Vauxhall Astra 3door and money (French British American any kaffir soldier take ur pick)."

He pleaded guilty to three counts of disseminating a terrorist publication and one of inciting murder during a hearing at the Old Bailey. His wife, who had insisted on wearing her veil in court, had admitted disseminating a terrorist publication at a previous hearing and is awaiting sentence.

Michael Adebolajo, 29, and Michael Adebowale, 22, will be sentenced this month after they were found guilty of murdering Fusilier Rigby. The British Muslim converts ran the soldier down in a car before hacking him to death with a meat cleaver and knives. They dumped his body in the middle of the road near Woolwich Barracks.

Barnes's lawyer, Naeem Mian, said: "Mr Barnes makes three postings on YouTube immediately after the death of Fusilier Lee Rigby which are to say the very least untasteful.

"About a month or so later, Mr Barnes posted on Facebook following on from a posting which details the rape of an Iraqi woman, saying he would reward anybody who murders an allied soldier with a Vauxhall Astra."

Prosecuting, Kate Wilkinson told the court that before the postings, Barnes had been involved with a sharia law patrol of London streets, ordering women in short shirts to cover up and telling people to stop drinking alcohol.

He was also a member of extremist group Al-Muhajiroun – or Muslims Against Crusades – taking part in demonstrations advocating sharia law in the UK, including one on 24 December 2012, outside St Paul's Cathedral with Adebowale.

The court was then shown all three videos and some other examples of earlier videos that Barnes had posted on YouTube, which were found in a police search of his home. The first video includes a clip of one of the Woolwich murderers talking with a knife in his hand in front of Fusilier Rigby's body. What follows is an on-camera diatribe by Barnes filmed by his wife, Dawson. The video lasts for seven and a half minutes.

In it, Barnes described the murder as a "brilliant day" and warns the prime minister, David Cameron, and the public that the attack will not be the last. He says: "You are not safe here, do you understand? British soldiers, you are not safe on the streets of London."

The second video shows Dawson in a face veil behind a title: "British troops kill Muslims so they will die on London streets."

She says: "Obviously now this guy who has been killed, Joe Bloggs or whatever his name is, was killed, this is the lion, the tiger fighting back... We are fighting back and sharia, obviously the Islamic law, will dominate the entire world … don't worry, it is coming Inshallah [God willing]."

The third video shows Barnes being filmed by his wife driving past the scene of the Woolwich murder to a loud musical soundtrack. They are heard to laugh repeatedly as they take in the floral tributes to the soldier lining the street.

As Dawson asks him to drive around again, Barnes says: "Now they turn it into a shrine where they are worshipping his flippin' shrine … Obviously the death of Lee Rigby is something to be ridiculed at, because these kuffar [non-believers], they fail to realise that their foreign policy is the reason why this Lee Rigby is no more [hysterical laughing] … he got chopped up in Woolwich …"

The first and second films were on YouTube for two to three days, while the third remained online for two weeks. Only the first video was removed by YouTube itself.

Another video clip retrieved by police showed Barnes at Finsbury Park tube station pretending to be a suicide bomber on the platform in front of other passengers.

The court was shown a further video of Barnes secretly filmed in the dock at Westminster magistrates' court being sentenced for a public order offence after an English Defence League demonstration.

Outside the court, he is seen on camera mocking British justice, and bragging that he is "free as a bird".

The last video shown in court was of a vigilante-style sharia muslim patrol in east London. Barnes covers his face in a scarf to rant about sharia law on the streets before a clip of a drunken man falling asleep at a bus stop with sound effects of guns being cocked.

Barnes, wearing a tunic, trainers and scarf, spoke in a clear voice in the dock as he entered his guilty pleas. The judge, Brian Barker, adjourned sentencing to a date to be fixed while reports are carried out.

He told Barnes it was in his interests to co-operate with the reports, to which Barnes replied "undoubtedly".