Why do people re-upload and spread around videos that don't belong to them? It's really fucking annoying... It even says who the actual creator was at the end :S
I think it's because yt doesn't have a good way to provide links and still notify subscribers, and the guy who re-uploads it wants to show his friends, er his subscribers, so he wants to have the notify function work.
Youtube might have it like that on purpose though, would be retarded if a guy who just uploaded videos from some other major channel and had almost as many subs. So they wouldn't want to automate the process maybe.