Because Britney Spears is busy being Britney Spears and is sadly unavailable to make a video for her new single 'Break The Ice' some other people have got some other other people to make a video instead.
It's quite good in an anime way but it is essentially rubbish.
REASONS THIS VIDEO IS RUBBISH
1. Britney isn't in it
2. The 'Britney' in the video doesn't even look like Britney.
3. In an era of fan-made YouTube videos featuring songs chucked over animated clips this is completely redundant.
4. In 'animated video to excuse absence of popstar' terms it's even worse than Five's 'Rock The Party' .
We could continue. They should just be honest about it and release something like this.