Hey bud, nice to see you.
You're right that DTube is far more reliable now than ever before. That said, I still think it needs to go from "usually working" to "almost always working", for it to really compete with the big mainstream media sites. I want that, really badly! So it's frustrating to see the site continue to be decent-but-not-amazing.
Good question about where data is hosted. I've wondered but never investigated. I keep a safe offline copy of everything I upload, of course, but I'd still like to know where the online 1s and 0s are.