Cool idea. Only thing I don't like about "like" competitions is it comes down to how many online people you know. Someone with 2000 friends on facebook who posts their video everyday to their page and tells all their friends to like it is going to get more votes than someone like say me, who has 40 friends on facebook. I just don't have anywhere near the online friends list to get that many likes, no matter if the other video is crap and the person doesn't even need the lights and mine had awesome production value and I showed I really needed the credit.
I just had friend who's a producer do this for a band they recorded and had them vote in a contest and I got spammed from them everyday to vote, so it comes down to who can spam the most people, not who's album was better.
My 2 cents anyways.
Yes, and if 2000 people somehow get wind of the competition/company because you spammed like crazy, then you earned your prize by providing free advertising.
It's the nature of the game.
A random drawing would be more fair but have little benefit to the company.