Those are traditional folk outfits. They're not dressed as nuns. But also fucking check out the guitarists rock out on this one.
Many feel that it's an enormous embarrassment for Poland to choose a cheesy song like this: but they're really missing the point. The worst part of the song is the lyrics, which are pretty lame; however, most foreigners won't understand the lyrics. The same works in reverse when trying to tell non-Poles about how great Pan Tadeusz is (the plot is super-lame; one reads it for the language, which is lost upon non-Polish speakers.)
Not all are detractors though. Some find the lyrics and tune pretty catchy (I myself have annoyed more than one co-worker with my incessant singing of "Ciesza sie Polacy! Cieszy Ukrainia!" (Note: I'm not endorsing this song or admitting that it's good, it merely entered into my rotation of songs to sing out loud for the Euro2012 duration.)
The last I heard, they were not going to perform this for the opening match.
Awwww shit, son! It's the remix!
This is not the first folk song inspired by soccer. Maryla Rodowicz also performed for the 1974 World Cup, in which Poland placed third.
All I can say is that I can't wait to see if this is submitted for the Eurovision contest. Won't that bring down the house.