I have just downloaded firefox 125.0.2 (32-bit) and tested it on another 32-bit Linux system (easyos) and it works - can play youtube videos!
firefox_getLatest.sh -m 113.0.2 also works for me and firefox 125.0.2 (64-bit) with tinycore64 too
I also tested the version of Firefox 125.0.2 32 bit downloaded in Teeny Core on Ubuntu 18.04 and I was able to view any video on any site.