It'd make a good BtVS plot line, but it wouldn't be an original idea. When the episode goes up, you can watch it
here - it's episode 10, Season 3 (even though we're on season .... lots in the UK, the numbering has started from when it was 'revived').
Don't worry about watching on the site, it's hosted in Sweden where it's not illegal to download stuff. I'm watching Season 3 Lost at the moment because I was one of the cable customers who lost access to it when Sky 1 and VirginMedia had their little spat. It's quite funny, all the Lost episodes come with subtitles. Mostly they're in French, but I have watched one episode with Chinese subtitles.