I don't agree the singles themselves became patchy. If that's how you're describing Beauty and the Beast then I'm afraid I'm going to have to fight you.
You often see the same archive clips appear over and over. Don't forget that rock music shows were extremely sparse on tv during the 70s so when they featured big names those clips will be endlessly recycled. As you say, it's nevertheless good to see them. One show ran the superb TOTP clip of Jean Genie thought lost until rediscovered 10 years ago.
That would be a pointless fight - Beauty & the Beast was from the late 70s. I maintain the 80s were patchy, as he released some very good singles then, but none after Absolute Beginners, & some before that weren’t up to the standard of the 1970s unbroken good run that lasted from Changes until Scary Monsters in 1980.
Re the clips, yes it’s a shame the BBC don’t have any contemporary film of Genesis with sound or vision half as good as their Bowie handful from 1972, leaving us with only those few clips from the early 70s on Youtube that have been immaculately refurbished by devoted fans.