I thought CBS' Superbowl Streaming was pretty good.
At least better than I expected. I wanted to try watching the US feed, so I enabled my VPN so I could access the CBS one.
For the most part it was HD (probably 720p) the whole time. Occasionally some frames would drop (making it jittery) or the resolution would temporarily drop.
The fact that those were the only issues I experienced with a sports event streaming in HD was pretty impressive. 10 years ago if anything was streaming live in SD it would jam up and crash. Give it a few more years and it'll be glitch free.