We should integrate YouTube Direct (but not as the only option) to make it easier:
http://code.google.com/p/youtube-direct/
Also, maybe we can recommend keywords to use on the popular video sharing sites so we can simply link to search results pages that contain relevant videos and people do not necessarily need to register and add their video to our site.
How about Kdenlive set up a YouTube channel, I assume you might already have one. People then can make tutorials or videos using Kdenlive and put them on their channel and submit the videos to Kdenlive for approval. Approved videos are then added to the Kdenlive YouTube channels playlist, a custom YouTube player is then embedded into a video page on Kdenlive.com
Below is a link to my embedded YouTube player with 3 of my videos from my YouTube channel playlist. Content is completely controlled from my YouTube channel.