From the video, it looked like Metallica had fun playing at BlizzCon over the weekend. Not sure the Twitch audience did though. They didn't really get to hear the performance...
Seems like Twitch was afraid of being hit with copyright issues, so they replaced the performance audio with some nice elevator jams. Not really sure that fear was warranted since it was actually Metallica playing the performance, but they did it anyway.
Luckily, I found the full performance as well. Enjoy...