I would hope Dtube fix the video availability and not take them down. Keep in mind that hosting all that video data requires a massive storage system.
The videos cannot possibly go on the blockchain. The blockchain is meant for small transactions such as money, votes, and text. I believe pictures are not even on the blockchain. The blockchain actually has links to the database that stores them.
If a blockchain had the ability to add pictures and videos to the blockchain, it would quickly overwhelm the nodes.
While your text and money is decentralized and protected by the blockchain, the pictures and videos are not. Sorry.
If you are truly in need of protecting your video work forever, here is how to do it. You secure a domain name and host the video streaming from a server that you own or from server space that you rent. Then create STEEM blog and link your video feed within the blog. The link is text in the blog, so it is forever stored in the blockchain. You then have the control of keeping the video available or taking it down.
I know that it is a lot of work and not really practical. But here is the catch, If you learn how to do this, you could generate your own Dapp video channel to compete with Dtube. You know Dtube takes a healthy cut of your creation rewards.....
RE: WE ARE STEEM