Britney's secret rehearsal video for VMA 2008?

Britney's newly released rehearsal video has sparked some major buzz on the Internet. An MSN insider reveals exclusively to BreatheHeavy.com that by 11pm PST last night, the video was already streamed 715,000 times - reaching well over one million by 12pm this afternoon.

The video, choreographed by Andre Fuentes, was shot in mid-August. According to Eonline.com, the song is called "Underground," though sources reveal to BreatheHeavy this is NOT the name of the track Britney is dancing to.

When asked about whether the rehearsal was for the Video Music Awards, an MTV rep replied "no comment."