Drupal 7 - Video Contest Website
You can do this with the Rules module, which includes a Rules Scheduler submodule.  (Node One tutorial on Rules Scheduler)
You can use Fivestar for voting.  To hide the votes, you should be able to use Views.


These are very general suggestions but it sounds like you're in the very early stages of your planning; if you have specific questions, you're welcome to post those later.  Basically, you should be able to use existing, well-tested modules for what you're trying to do, although you may need to customize them from time to time to match your specific use case.  It's generally not worth your time to write modules from scratch, except as a learning exercise.