Yeah Dtube deletes old videos off their servers after a while :( It is in the FAQ in their Discord server and probably in the terms of service I would guess. What I would recommend if you want to try out DTube is to use it in addition to Youtube - that way you can upload a clip to DTube but still include a link to the Youtube version in the body of the post so you don't end up with an empty post down the road when the DTube video is deleted. Also, DTube has terrible issues playing videos depending where you are in the world, so providing a youtube link as backup is a good idea for that reason as well. Cheers