He recorded it last night due to the xtrafactor.

http://xfactor.tellymix.co.uk/news/6...e-tonight.html

I went to last night's show the article is 100% correct, Olly performed it just before yesterdays show.

But he sang it live yesterday at least didn't he?
He is so good live.

how does that work??

No he is not. It is like watching a circus act. Trying to sing with daddy dancing. He really is bad singer and reason why this had to be pre-recorded.