You can find several videos showing the detonation of the Tsar bomb, a Soviet nuclear weapon (strongest ever tested). Most of them are bad quality and look very old. But also you can find this video:
World's Most Powerful Neclear Bomb - Tsar Bomba - YouTube
This is very good quality, looks newer, and is from different angle than the other videos. Is this is a real video of the Tsar bomb, a video of another nuclear explosion, no real video at all (computer animation)?