The video of the infamous collision between Japanese coastguard vessel and a Chinese fishing boat off the disputed Diaoyu or Senkaku Islands in September was recently leaked and surfaced on YouTube (below).
From the YouTube video, the Chinese fishing boat--Minjinyu 5179--collided twice with Japanese coast guard ships Yonakuni, and another collision with patrol boat the Mizuki. The whole footage was 44-minute long, and only the actual collision part is posted here.
The video looks like was taken from the Japanese coastguard boat, and had previously only been shown to Japanese Prime Minister Naoto Kan, security officials and some lawmakers, but not released to the public. Japanese foreign minister Seiji Maehara told a parliamentary committee that the Japanese government would investigate the leak.
Chinese Foreign Ministry spokesman Hong Lei said that the collision had occurred because the Japanese coastguard was undertaking "illegal operations" within Chinese territorial waters in the East China Sea. "The so-called video cannot either change such a fact or cover up Japan's illegality," Hong said in a statement on the ministry's website.
From the news coverage I've read so far, most marine experts believe these leaked videos do not establish that the Minjinyu 5179 deliberately rammed the Japanese ships.
Meanwhile, Google's got flack in Japan over these leaked videos as well. Tokyo prosecutors have seized Google's records in order to investigate how the leak managed to happen.
Some worried that this could reignite more tension and dispute, but I personally don't think things could get any worse regardless of these leaked videos.