I have since learned that Dtube only holds videos in storage for 14 days (afaik). After that they are deleted, apparently due to the cost of storing them. Youtube didn't actually make a profit for most of it's life - probably for the same reason. DTube's operator did state that videos would be stored for longer at some point - but obviously that hasn't happened yet. Dlive does at least play the videos back reliably right after they are uploaded, which DTube is having problems doing.