When an actor, director or otherwise famous celebrity is portrayed as Good-hearted, drug-free, abstinate or straight but in real life is an addict of some kind, rude or most likely gay. Generally used to describe any personality that plays someone or claims to be straight and in actuality is on the down-low.
"Although Tyler Perry plays a woman in his movies, I think he might be Behind the Scenes"

I heard that Neil Patrick Harris does a little playing "Behind the Scenes"
by mrsmartguy July 5, 2011
When your friend is doing someone Doggy style and you stand behind them naked and move their hips.
Man me and jimmy behind the scenes Dutch rudders her and she had no clue
by Mike Oxtasty May 1, 2020