I used to use a program called Mac VideoRipper Pro. The old website says that it is no longer for sale, but you may be able to find a site that still has a free or trial version.
Note: I am still on Mojave because there are some programs I have that cannot use a newer version (64 bit?), like my Flamenco Metronome, so maybe this is no longer sold because it uses 32 bit instructions.
Maybe
this? I haven't downloaded it (Vidmore streaming video recorder), so don't know anything about it, but it looks like there are other free programs available using a search for streaming video recorders.