Woovit has been designed to be automated, so you don't have to manually "submit" your work. We "crawl" each of your attached accounts to look for videos that match the offers you've taken. We then report the videos back to both the creator's account (under the "Delivered" tab) and to the Publisher.
If we missed your video or videos, you can manually select a video or stream from your channel on the relevant campaign page. Look for the campaign in your Accepted offers tab, and then go to the bottom of the "How to Deliver" section.