That was Glyn Johns attempting to turn George Harrison on to Zep, to little avail, unfortunately.
http://teamrock.com/news/2014-10-31/beatles-and-stones-dismissed-led-zep-debut
I'd have to disagree with 75 being the high point for Dazed, 73 was the zenith imo. Perfect length, all the different sections and improvs still had a sense of purpose and direction. 75 versions started to meander a bit too much.
Saw it in the theatre earlier tonight. Enjoyable and well made, although no particularly new information. The thing that really made it worth it was that they showed the entire 1965 Shea Stadium performance after the film.