The interesting thing about this is that it was Metallica playing Metallica, which, considering their actions during the whole Napster affair, is rather amusing:
Long time copyright watchers know that Metallica sullied its reputation with tons of fans when it was the first band to sue the file sharing upstart Napster back in 2000 (and also sued three universities for "not blocking Napster"). The band's drummer, Lars Ulrich, became an outspoken critic of file sharing and the internet, the early face of super wealthy musicians whining about the internet changing the way they did things, leading to the classic Money Good! Napster Bad! meme.
Over the years, Metallica has tried to do more to "embrace" the internet, but almost every time, fans jump up to remind them about what assholes they were towards the early internet experience.
And that brings us around to Friday evening, when Metallica was set to play a streamed "live" show to kick off BlizzCon (an event for video game company Blizzard). The event was streamed live on Twitch, which has had some copyright problems of late. It appears that as Metallica was playing, and the Twitch Gaming channel was streaming the concert, someone realized that there might be a copyright problem. As first called out by Rod Breslau, the channel inserted 8-bit folks music over Metallica's live performance to avoid a situation that, uh, Metallica might sue over.
This is sweet, sweet payback, and I expect this to get memed to death.