Youtube had gotten near unusable for me until I blocked the XO mirrors and that worked great for a while. Then that sucked even worse (most videos just errored out). Removed it, and streaming has been actually perfect since with barely running into any buffering issues.
Oh, I found if I set it to 720p it'll continue to buffer even if I pause it, which is pretty great. I'll get a few different videos buffering then go make dinner or something, then when I come back the videos are all totally buffered. I can usually directly stream a single 720p without issue, sometimes even buffer one while streaming a second.