Exploiting Firefox DRM plugin to get decrypted content

[Pasmoke]

I know there are plenty of threads discussing about how to download encrypted data but I wanted to discuss an alternative method, especially since in theory it wouldn't required CDM keys, license URL or an MPD.

To be more precise what I mean is to use the DRM plugin that every browser has (I take Firefox with Widevine plugin as an example) in order to decrypt the encrypted video and audio frames that you download. This is something that the browser itself is already doing if you think about it doing so do you think it would work if someone could potentially isolate that code that does it and make it a third party tool specifically dedicated to this?

I tried answering myself and picked up Firefox source code, compiled it and started to look around. I spotted the code that sends the data to the plugin and gets back the decrypted data but unfortunately, not being a C++ programmer, I'm having a hard time navigating the code and I'm not sure how, in the end, get the raw frame data so that I can recreate the original video.

Is this insanity or could it work? I'm starting to think I'm probably missing something obvious since, after doing my research if other people have thought about this, I came up with nothing.

[notaghost]

something like these?
https://github.com/Rafiuth/ChromeFrameDumper

[Pasmoke]

something like these?
https://github.com/Rafiuth/ChromeFrameDumper

Something of that sort. But my idea was actually interacting with the plugin that does the decrypting so that you don't need the frida scripts or hooking functions since the code that does this is available, but seems like I've punched above my weight.

[notaghost]

Tubedigger 7.8.2 now supports this feature.