In that sort of situation, you should still tell your teacher and even tell the police. That's more than just bullying, that's assault. Also, even if that video gets uploaded, the police can get it taken down and it would ruin that boy's life more than it would ruin yours. Ugh.
ah yes, the good ol blackmail "if you dont do what i say, i will upload this video of me commiting a crime, which in itself is a crime", flawless logic.
and from the sounds of it, the home life is even worse.