The number of ullage rockets on the interstage between the S-IC and S-II stages changed, with 8 on Apollo 4 and 6, 4 on Apollo 8-14, and none at all from Apollo 15 onwards.
Are you sure about that? I remember some rockets being deleted from Apollo 15, and that resulted in the S-II plume hitting the top of the S-IC and killing some telemetry transmitters. It wasn't a catastrophe since the S-IC had already done its job, but I recall that some rockets were put back on to prevent a recurrence.
Jason is correct about the number of ullage motors. What you're thinking of, ka9q, are the retro motors on the S-IC stage. There were normally eight of them housed in the F-1 engine fairings. On Apollo 15 the number was reduced to four, however this was increased back to eight starting with the very next mission.
Yes, I am very sure. The S-IC ullage rockets are very clearly visible on the interstage, so it's a simple matter to see how many were on each rocket. If retro rockets were changed I don't know, because they are not visible on the S-IC, being inside the engine fairings.
I think you mean the S-II ullage rockets were on the interstage. The S-IC didn't need ullage rockets. :-)
But yeah, Bob, I was thinking of the S-IC retrorockets that were deleted from Apollo 15 and restored on Apollo 16.
The Flight Journal for Apollo 11 has some clips, including the one shown in the first post of this thread. In the Flight Journal (at GET 000:10:01) the authors - David Woods, Ken MacTaggart and Frank O'Brien, confirms it comes from the Saturn 1b launch AS-202