Also understand that Deluxyzes run was when no one else was competing. Never even used bunny hops. If someone were to do the exact same run or even slower strats but utilize bunny hops in most places they'd easily beat the time. And people are already attempting to break the game in crazier ways. So don't base your odds on that original world record. It's going to get halved at least MINIMUM.

As for the original question, you can stream it anywhere. I'm sure they'd prefer it to be on the main platforms Youtube, Twitch, Facebook. But I think they'd accept other platforms as well as long as they are established. If your computer is decent even if your internet is bad you should be okay streaming at super low quality. Depending HOW BAD it looks they might decide to not accept it. It'll come down to if certain parts can't be seen properly. Bad quality = a lot more chances to do fishy stuff because it's just harder to see anything for the mods.

Pretty sure they did say that it has to be from Steam. They are being a lot more strict with this one in terms of rules. They did say other platforms may have the game but I'm not sure if they okay'd that. Because different versions do have little differences in them. So even if they did allow pirating you'd have to make sure it's the CORRECT version of the game or it would be invalid. And finding an exact version would be the hard part when it comes to piracy.