It seemed some kind of monsters took over after a while
(possibly NSFW due to monster makeup and some stage gore)
And then it got weirder
In case you don't recognize them, the monster band was Lordi. Their music is pleasant enough if you like that kind of metal/hard rock, but their charm lies in their stage antics and showmanship. And they delivered on that front - the show was very fun, if a bit short (90 minutes), but I guess rocking out with all that gear on is exhausting.
(they sound "harder" live, the music in the videos is a bit more "pop")