Ah, another clipshow film, and is the worst in the Godzilla series. There are some similarities between All Monsters Attack and Gamera Super Monster, with all the fight scenes being recycled due to budget reasons, and it's down there alongside Truffaut's "Love on the Run" and other films marketed as a sequel but had few new scenes that were worthwhile.
He didn't mention in the commentary, because it was maybe obvious for older generations, but the film was made almost a full decade after the previous Gamera film. The kids in the movie - also the target audience were barely tots or not alive at the time those films came to theaters. In addition this was before video rentals were available, and Gamera films were not frequent broadcasts on Japanese television, as they were filled with an overcrowded time of Sentai and other hero, robot and monster shows. The kids that went to see the film in its theatrical run had most likely never seen the previous films and the fight scenes were completely fresh to them. Sadly, the dated effects of the stock footage, badly edited storyline were not enough to get audiences back, and in addition, the older Gamera fans either outgrew their fandom or were frustrated to see that all the fight scenes were old clips entirely.
Though this seems to be something impossible in the age of video and the Internet, I was surprised to see something similar recently. BBC Nature's theatrical film "Earth: One Amazing Day". I wasn't aware that this was mostly a clipshow film, taking footage from "Planet Earth II". But at least there was a good amount of interesting new footage included.