The Youtube post says,

We’ve seen a lot of footage of the tragic Japan tsunami, but this clip is the most horrifying yet. Entitled “South Sanriku — Tsunami seen from Shizugawa High School,” it’s shot from high ground, but toward the end of the video you can see panicked residents running for their lives.

Almost as dramatic as the video is its audio track, where even if you don’t speak Japanese, you can tell the people are expressing concern at the beginning, but by the end, their voices have reached a high level of panic and horror as they watch their homes washing away.