OK, that pretty much confirms my own suspicions. I suspect IPFS is immutable. We are running some large scale IPFS servers in our data centers to help contribute back to the free and open Internet in some way. We have a lot of unused bandwidth and I'm very happy to donate as much of this unused resource to IPFS simply because it isn't helping anyone to have it go unused. I know that if I put up some content (video, audio, whatever) on IPFS, it is permanent. What is not permanent is the indexing to it. I guess this is similar to the old BitTorrent thing, where the torrent files that point to the content could be taken down, but the content itself is out in "the cloud" and you can't roll it back. So if d.tube got co-opted, taken down, etc. I suspect that if it was open source and could be forked, someone would simply fork the database and create a new d.tube.
These are all assumptions, of course. I'm probably wrong on some/all of them. But it would seem that the database and source code that powers d.tube should be put somewhere in the public domain so that all the work that hosts are doing and uploading, can be brought back to life in the case where d.tube is attacked by an adversary.