I'm confused about how open source DRM can even be a thing. Presumably once you've obtained one of these client identity files, you can modify OpenWV to capture the decrypted / raw video to wherever you want?
There were some open source white box cryptography attempts fifteen or so years ago and they didn't work because of precisely what you say.
OpenWV is implementing the decryption itself:
But it still isn't an example of someone shipping an open source DRM module - it's just software to crack DRM with a leaked key.
(Incidentally and this is not legal advice, but if you are in one of many European territories and downloading software from Git here I would encourage people to think about the possibility you are committing an actual criminal offence by doing so, as you are "importing" it by virtue obtaining it from a US entity.)