It isn’t quite the same. Vimeo business model is paid subscriptions. So, as long as you pay, you can upload more. If it becomes a problem, just pay more, and you will pretty much always be good to go. If I’m not mistaken, there won’t be any easy way to monetize the video content, except by adding ads in the video yourself (we could always imagine your plugin doing this one day, but you would still need to find the advertisers, make them pay, etc. And it wouldn’t be easy to change ads and so on. Not very good in any case).
On the other end, Youtube would allow a forum to monetize easily the uploaded video content. If that was uploaded to an account belonging to the forum. A quick search say that limits are pretty high (100 per day, with a limit getting put in place at 50 per day if you hit 100 one day), BUT seem far more limited when you use the API, as you’re saying (I also saw the number of 6 per day).
It would be a great option to be able to choose how to upload to Youtube: Common account or individual accounts. The big question is if forum owners would be able to get this limit increased with youtube. I don’t think you should tell them several people use the account, but that the account belong to an entity (the forum), and it’s the entity which uploads. A question of how you spin it. You would maybe need (and that would be your best interest in any case if it’s with your account) to check the videos before upload: An option to store the videos locally for approval before upload to youtube ? And an option to limit the number of uploads per day (to be able to start with a limit of 6) ?
That’s a few suggestions. Do what you want with them (they rely on the fact that it would be possible to get the limit increased. I’m not sure at all how possible that is. But it sure would be great).