This wasn't a server-flood crash. Even the Apple TV stream was doing competing bands right from the 09:45 start. Maybe the other band stream was what became the Chinese (?) overdub - I don't know. This was fixed about 30 minutes into the presentation.
The video had been OK, although with the extra audio, but right as the event started - everything died. Errors on Apple TV, "test pattern" on Safari. I had to quit and restart safari a couple of times but got "some semblance" of the presentation.
But the stall, dropouts and freezes continued.
This was, without doubt, the worst Apple presentation I have ever seen (and I have seen quite a few). I don't know what failed but this part of it wasn't being handled by Apple directly - it's all done by specialist contractors (think: WWDC). Apple does the organization but other folks set up and run cameras, do TV/satellite links etc etc.
For these folks, Wednesday will not be a pleasant day.