Top post of the thread actually does say!
At this exact point in time I would prefer that people not stream the beta publicly just because it's JUST launched and I'm still waiting for people to verify that it is running on their systems. Streaming it later during beta will be fine - you own it after all! I'd just prefer a little bit of quiet time first.
It's not, like, legally prohibited, I'm not gonna sue you or anything, but I'd prefer people wait just a little right now. Especially since not everyone even has their beta keys yet.
So I'd prefer people wait, I'll probably edit that in a week.