Would it be possible to log all the 'embed' code somewhere so when a person tries to submit a video and it's already on videosift, they would get a duplication error? Seems like something similar to that would save Dag and others time deleting dupe posts..

Unfortunately, people don't use very good tags sometimes so just trying to search for a video you want to add that is already on videosift will not always be found. It's happened to me a few times.