First, they don't usually change films when going to home video, so it's unlikely they removed scenes from the theatrical cut before it went to video. Second, I saw the same film in theaters and I don't recall the scenes you are discussing. It's more likely you're misremembering or that you somehow saw a preview screening of the film before its finished form. Have you tried looking at the screenplays for the film to see if any of what you're remembering was in it?
I have a clear memory of watching Back to the Future part 3 in the cinemas, and there was a bit of dialogue cut from the scene where Marty's going back in time at the drive in. Doc gives him a gun and says that if Marty can't save him, get the son a bitch who kills him. I remember it clearly because I was only about six or seven at the time and I was surprised they sad a naughty word.