Well I'm not sure about that. They can use the entry to promote the event, which promotes the winner, plus as a winner you get a prize. It's a fair exchange. It's not like. Any budding DP would gladly sign up if Rick McCullum likes what he sees and hires him/her for the next project. It's a fair demand that is pretty much standard in most competitions.
If they only want to promote the event, why are the rights not restricted to "event promotion" and time limited? Worldwide unrestricted rights is very broad indeed.
And why to they want the rights to use all the entries, not just the winner? Losers have to surrender their rights too? Remember, only the winner gets the prize and exposure. Losers have surrendered their rights to the organiser and Canon and get nothing in return.
Its high risk. You have some great footage but it's not placed. Canon and the organiser can still do whatever they like with your footage......they are under no obligation to credit so who is exactly winning here and why is this fair?
Pro-imaging run a "Rights On" and "Rights Off" list for good and bad photographic competitions. They actively challenge those competitions that grab rights to images, and promote those that don't. Is there anything similar in the moving footage world? If there isn't, there should be.