I've had nothing but great experiences from the Justin.tv/Twitch.tv team regarding their tech. NASL and Dreamhack both just had fairly crappy streaming setups and equipment, in my opinion.
I'm on a high end gaming PC with oodles of RAM / SSD / i7 on a 50 down 10 up connection so I don't think that watching a stream in 1080p would tax my computer too much.
I also don't think it was the NASL team's fault because the same thing happens on other streams periodically.
It seems to be a bandwidth issue from justin.tv to the end user but it could be anything, all I know is that it is quite annoying.
The next few days everything worked great again.