As bad as it might make you feel that this one person got all his friends to hate on you, just look at it this way:
There's no such thing as bad publicity!
If that guy is getting all of his friends to traffic to your video, then you're getting all of those views! And what he says really doesn't matter. If you have your friend's support and are happy with what you are doing then don't worry too much about one video. Keep at it! Look at all the bad publicity from Miley Cyrus lately, but guess what, she's all everyone can talk about! Yes it's negative, but don't sweat it and enjoy the traffic. :]