Such a good movie... Do you happen to know which spacecraft this was?
https://www.youtube.com/watch?v=VUQgBPjGmAQ#t=35
AFIAK no one has ever done an exhaustive analysis of the provenance of all that stock footage.
This is an example of someone chasing it down. I don't think it's been done for all the Saturn V launches (Apollo 4 thru the last Skylab launch). That would be a big ask.
https://www.youtube.com/watch?v=HBITROWVcok
As a kid growing up in the 70's it was perfectly normal to see a documentary about Apollo 11 where they throw in the Apollo 4 Stage 2 ring separation like it was no big deal. The awareness of all these subtle differences is a recent development.