The Compleat Beatles (rel. 1982) is the first definitive Beatles documentary released. Although the ten-hour Beatles Anthology of the 1990s has much more detailed content, The Compleat Beatles is still a great documentary and fairly comprehensive in its own right.
I could tell that the producers spent a lot of time to make a great film -- it's no slipshod production here. It includes plenty of material that make for a delightfully filling viewing experience, and includes hints of subtle humor in the narration that the early Beatles were known for.
The pacing of the film is good too - I could only see two places where I was scratching my head why something was put in.
Expertly narrated by Malcolm McDowell, The Compleat Beatles seems to contain all important aspects of their career, with a more tilted focus on the band's formative years and once they broke through versus their later years. Their final years are given good coverage, though.
The video also includes full showings of important points in their career, including most of their performance on Ed Sullivan and the full presentation of All You Need is Love for the world event they did it for. That was a delightful addition. Its soundtrack includes lots and lots of music - almost every hit is included.
I've seen this video about ten times over the years, and it maintains its quality for multiple viewings.
Overall, The Compleat Beatles is excellent. I am not sure if it is on DVD, but you can find it on VHS easily.