I don't get what Universal's PR team is planing. You can record, and live tweet, but no streaming it.
If they'll have an official stream that could be a reason, but at the same time people would probably just not stream if they were told that.
And I also don't see Universal using an entire 20 mins block of TV to a presentation on a stage, only if it was edited (kind of like a Nintendo Direct), and you can't do that live.