I guess it depends on the circumstances otherwise we know what it borders on. Junior would have had to have seen his brother's "treasures" before he seemingly eagerly pulled back the sheet. But I congratulate him on his restraint. My mind went elsewhere.
I remember that vid he made we someone that was sort of a private casting video well before there was OnlyFans and its iterations. He was filming he and this other guy fucking. The other guy was hot also and it seems like he was being taught how to be filmed. Can't remember the name of the film but Al Parker was really a presence.
Despite my fantasy, I believe it is light from the camera taking the pic. However, nothing better than grabbing the middle of the thong with your teeth and then make a dash for the hole. Or maybe that's just me.