Music like you've never heard it before

Saw this on late night TV and almost wet myself. check out the guy in the bottom right hand corner. he's signing the lyrics of the song, but getting well stuck into it! London has a thing where it tries hard to cater for the deaf, which is cool.. eg you often have signers on certain channels for the news and some TV soaps... But, surely this begs the question...wouldn't it be easier to use subtitles?