This is a strange one. Weezer played a couple of random promotional shows last week. This is from a T-Mobile show promoting the release of some kind of new Sidekick product (Rivers mentions both in the song's intro).
I would first like to state that the actual versions of both songs Weezer covers in this video both suck. "Kids" by MGMT and "Poker Face" by Lady Gaga are both terrible. I hadn't heard either song but I knew they were popular. I had to check them out and I was appalled at how bad both of them are.
The keyboard/synth riff in the MGMT song however is actually pretty decent if not exceedingly simple. I think it's pretty catchy and the "Poker Face" part by Weezer frontman Rivers Cuomo is comical here. It's cool to see him enjoying himself and sans the moderately creepy mustache.
Some interesting notes to me at least: Rivers went guitar-less at this show, giving drummer Patrick Wilson lead guitar duties, though everyone plays keys in this video.
That's Josh Freese back there on percussion helping out. Freese has played with a lot of groups including being a member of A Perfect Circle, Nine Inch Nails, The Vandals and Devo. He's a well known session player and has worked with countless others. No word on if he will join the band touring this summer but I think this was just a fun thing to do for all of them.
You never know with The Weezers though.
For some reason the width on this video is super widescreen, it was clearly filmed on one of these cell phone contraptions so it isn't in HD. Go here if you'd like to watch the wider version.