JPJ is also in this...at about 32seconds in:

Looks a bit like Stanley Kubrick...

Based on the jacket he's wearing, I'd say late 1966 (Oct-Dec).

Rick Beato's channel has a lot of great videos. Zep fans (particularly musicians) will appreciate his breakdowns of Ramble On: and Whole Lotta Love:

It seems like everything is on Youtube... Royston Ellis backed by Jimmy Page (unfortunately we don't see himJimmy). The low number of views makes me believe this hasn't widely been seen. Jimmy plays from 3:20 - 4:20.

Yardley's tour dates from Melody Maker, Apr 13, 68:

A few clippings from Melody Maker (second one mentions a Bonham solo) (July 6th, 13th and 20th, 1968). Also, re the Tim Rose appearance on Top Gear (July 1st, 1968), although Dougie Wright is listed as the drummer (source), that sure does sound like it could be Bonzo. Maybe it's just wishful thinking. Have a listen here. Track 1 - Roanoke: drumming with his hands (1:55) Track 2 - Foggy Mountain Breakdown On Rye With Mustard: multiple drum rolls (e.g. 4:34 & 5:00-5:20) Track 3 - I Guess It's Over: drum rolls throughout [triplets?] (e.g. 6:40, 7:00, 8:16, 8:20 ...) Track 4 - Long Haired Boy: multiple rolls throughout but harder to make out (e.g. 11:00)

https://www.theguardian.com/music/2020/jul/09/rolling-stones-jimmy-page-led-zeppelin-lost-song-scarlet

Mark Lanegan’s new album Straight Songs of sorrow features JPJ on keyboards on Ballad of a Dying Rover. http://www.marklanegan.com https://www.youtube.com/watch?v=3alMP5Jj-YU

I have them as playing the Corn Exchange on the 23rd of May, and at the Tiles Club in London on the 26th.

You can hear the guitar come in at 1:50 and at 3:22. I agree that it's fairly straightforward. I wonder what the back story is.

So on March 4th, 68, was Bonzo playing with Tim Rose, or the Band of Joy, or both?

Little Robert Anthony top right... From this page which has a bio of Listen: http://www.brumbeat.net/rplant.htm