Book B is the name given to the specification of DVD-Video, a consumer video format made for DVD discs. DVD-Video is a commercial success, currently dominating the market for home video. Video stored on a DVD disc must be MPEG-2, and supported audio formats include Dolby Digital (AC3), DTS, PCM and MP2.
For content protection, DVD-Video is protected by the relatively weak Content Scrambling System (CSS) protection. Region code restrictions are also included, where a DVD player will not play back a DVD-Video compilation if its region is not the same as set in the DVD player (DVD player region codes can be altered). PUO (Prohibited User Operations) also restrict the user from performing some actions such as fast-forwarding or skipping past warning messages.
There is also...
Book A (for physical DVD format specification)
Book C (for DVD-Audio)
Book D (for DVD-R)
Book E (for DVD-RAM)