11:08 PM PT -- Ribeiro's attorney, David Hecht, is downplaying the clip, telling us, "On numerous occasions, Mr. Ribeiro has commented on his inspiration for the dance. In the clip, Mr. Ribeiro used the word “stole” in jest. He did not use the word 'stole' in the legal sense."

He continues, "In his words, it was Ribeiro's (a professional dancer's) interpretation of what a white person looks like when they dance. That describes a copyrightable choreographic work."

Alfonso Ribeiro's past just bit him in the ass in his Fortnite lawsuit -- because he ADMITTED he stole the very same Carlton Dance moves he's suing over ... and the confession is on camera!

Here's the deal ... Ribeiro is suing the massive video game -- along with NBA 2K -- claiming they ripped off his signature moves without paying him a cent.

In his lawsuit, Alfonso claims he created the dance and is currently in the process of copyrighting it.

The problem for Ribeiro -- April 23, 2012 -- the day he looked into a TMZ camera and explained how he "stole" the moves from Courteney Cox and Eddie Murphy!

Alfonso says decades ago he was tasked with creating a dance for 'Fresh Prince of Bel-Air' -- and essentially wanted his character to dance like a super white person.

So, he thought to himself, "I know exactly -- I'm going to steal it!"

Seriously, Alfonso walked us through how he took Cox's moves from the Bruce Springsteen "Dancing in the Dark" video and meshed it with Eddie's famous "White Man Dance" -- and voila, Carlton Dance!

The question now ... can you successfully sue someone for stealing something you admitted you stole yourself?