The 56-year-old judge uploaded a video of Eric sat in front of the TV, while 'Vadik and the Bear' performed on stage.
While the act danced along to MC Hammer's 'Can't Touch This', Eric created his own dance moves by shaking his hands from side to side.
The person filming, most likely to be his mum Lauren Silverman, can be heard giggling behind the camera.
And it wasn't only Silverman who found it funny.
By the end of the video, Eric began giggling away and laughing to himself while flicking his arms in the air.
Whether 'Vadik and the Bear' make it to the final Royal Variety Performance or not, they've already got one upcoming gig in their diaries.
"Honestly I think it’s my favourite act of the series so far," Cowell said on the show, according to Radio Times.
"In eight month's time Eric’s going to have a birthday party. You’re hired."