Russia just declassified and released a 40 plus minute documentary highlighting the development and successful 1961 test of the RDS-220 "Tsar Bomb," a hydrogen bomb with a force of 50 million tons of TNT. Here's a video snippet:

Although some of the footage has been available for years on Youtube, this is the most comprehensive video to date, with never before seen clips and information. Embedded below is the full 40 minute documentary with subtitles.