Here's a tip if you want to get people to submit more videos. Include a "Submit Video" button in each area. When someone knows of a great video for a category, having to sign up for an account is a huge hassle and de-motivator. So just turn the onboarding upside down. Make it easy to submit a link first.
Once the link is submitted, THEN ask them to fill out the Username/password/email. At that point, they're already invested in the process, already submitted the link, and it's a lot easier to finish.