I thought they fixed this.
I had this conversation a month or two ago with someone. At that time I tried playing my first d.tube upload from May 29, 5 months old, and it worked, now it doesn't. Only my videos newer than 2 months work.

@dtube this is a MAJOR show stopper. You will lose users and you may lose me. I'm willing to setup my own IPFS node, so I'm willing to spend time and money. In other words I'm also willing to pay for my long term storage if you had that option.
If the old videos aren't available anymore you need to have some kind of informational "error message" saying so, just letting the web client sit and spin is going to discourage everyone, thinking your service doesn't work.

At the beginning of this venture I was looking at setting up my own IPFS node so this wouldn't happen. Looks like I'm gonna have to do that AND most of my videos are unplayable.

Not happy. :-(