I've never heard anything of her before, I think she has a nice voice, but she shouldn't profane this song with this performance (Yeah, her blond head on the silver plate, which she mention in the song could be a redress for me :P)
I guess she could record a 'nice' "Viva la vida" version at the studio, with more than just a piano, maybe even with Coldplay, but I do not think that it is necessary
Well and comparing to Solange's version ;/ - this is a masterpiece. ;)
The original video was also unavailable in my country, but I found this - maybe it will work for you?
http://ladygagafanpl.wrzuta.pl/film/7GRbqFScFiU/lady_gaga_spiewa_viva_la_vida_coldplay_live