Spoke too soon. Yes, it stalled on me twice at two different points. My solution on the third try was to pause it right away and let the whole thing download. Otherwise, for whatever reason, it would stop downloading sometime during playback.
I've been meaning to watch this for a while - this thread tipped me towards it, and it just played perfectly for me.
Incidentally, whilst talking about Velocity Envelopes, Gary Rebholz said that he very frequently uses it to create freeze frames. So do I and many others - all the more reason to include a "Set to Zero" option on the drop-down, to save a step each time.
In other words, instead of:
Right Click > Set to > Type "0" on keyboard
Right Click > Set to Zero
Yeah, I think the webinar must be hit and miss. On my first try I had to pause in the middle for an hour so and that could easily have timed out my connection.