You uploaded a video, you seo'd it to the Nth degree, yet some other joker was out ranking you all over the place, and even had a lot more page one rankings in Google for a lot of keywords that weren't even in the title, description, or tags of his video? You just couldn't understand how this person is managing to do this - Does Google just love this guy for some reason? Actually, No.
ALL THAT HAS HAPPENED HERE IS THAT THE OTHER GUY IS USING A LOT MORE TAGS THAN YOU THING HE"S USING. WHILE YOUTUBE IS KEEPING THEM FROM YOU ENABLING HIM TO RANK FOR MORE KEYWORDS IN BOTH GOOGLE AND YOUTUBE