I didn’t watch it myself but I did check a few times and had no buffering issues at all. That was being served from Netflix caches hosted by the ISP and I know there were no other congestion issues within the ISP :)

I’ve seen some discussion elsewhere though that some ISPs hosting Netflix caches were seeing all ports on those caches maxed out which would have resulted in buffering for users. They probably need more caches or Netflix needs to better direct users to caches with capacity (I’m not entirely sure how they are doing that). Other ISPs just didn’t have the spare capacity in their networks to handle it.

We were sort of lucky here in Australia because it was on a Saturday afternoon so it’s not a time when there is a lot of traffic from business customers and it isn’t at the usual residential night time peak.