I've seen this three or four times on the Bio channel. It's OK in bits but I was kind of disappointed. The most interesting bits were the bits Tony Palmer {the English journalist who says he was invited to go on the road with them for three months} commentates in. I found him interesting for this reason; back in 1979 when I was 16 and had just taken a major musical turn by discovering early Pink Floyd and Deep Purple, I was given or bought or gave books that all had something to say about this band called Led Zeppelin. The connections were weird; biogs on Rod Stewart {Zep ref via Jeff Beck}, Eric Clapton {Zep ref via Yardbirds}, this book on album covers, "
The album cover album" that had the covers of the debut, Zep 3, HOH and Presence, the "Rock on " 1980 annual that I bought for my sister that had this A-Z of heavy metal in it that said of Zep "kings of heavy metal, masters of their art, innovators....." and had this superb little article called "A fan's eye view" that said, among other things "You've got to admit, they're pretty bloody cosmic" (I've long thought that would make a great album title), this shitty paperback rock encyclopaedia from about 1971 {in Nigeria in those days, you bought whatever varying stuff found it's way into the country}, it was awful............and "All you need is love ~ the story of popular music" by Tony Palmer.

It's a strange book, it's really well written and Palmer spoke to an incredible array of artists throughout popular music's then history {I think it came out in '76}, people even from the 20s, 30s, wild. But some of the book is so hard to read. It gets better from the 50s on. There's a section there on Zeppelin although it's really focused on Jimmy Page. That's where his quote of "I hate my music being described as rock and roll" comes from.
Anyway it was interesting to put a face and mannerisms to the name. Palmer's book played an important part in my nascent research back in them days. It helped really whet my curiosity about this band. Suddenly, I wanted to hear their music more than anything else in life (that and "Deep Purple in rock").
The other bit I like in the documentary is when Peter Grant recounts the story of the promoter that pulled a revolver on him because he was witholding $1000 from Zep and Grant went to collect. He says "You won't shoot me for $1000. Don't be so fucking cheap !"
So English !!