The codec is the argument

A whole film on one disc, and a codec that was never meant to ship

DivX ;-) 3.11 Alpha was a hacked build of Microsoft's MPEG-4 implementation. It made a feature fit on a CD-R, and a company formed around what followed.

The open-source answer had to be written twice

XviD was rebuilt from scratch after the earlier open project's licensing collapsed, and it stayed compatible with the same decoders.

H.264 is still everywhere, and that is the achievement

Standardised in 2003, H.264/AVC remains the format with the widest hardware decode support of any video codec, two decades after ratification.

AV1 was built to be free, and free took years

The Alliance for Open Media published AV1 in 2018 as a royalty-free codec, explicitly to get out from under the patent pools.