- HDCP had flaws and keys up to version 2.1 were extracted/reversed. In addition to that there is hdfury device that legally and following HDCP licencing terms downgraded 2.2 to lower 2.x versions to provide compatibility. They got smarter and blocked downgrading in later versions. Blocking HDCP older than that would also break compatibility with devices that don’t support versions of the standard newer than late 2012. Add a capture card and you are set.
- Widevine L1 keys were extracted from a Qualcomm CPU in 2021. They are also stored in Intel CPUs in SGX which had so many flaws over the years I’d be surprised nobody grabbed keys at some point
- Both audio and video has to be decrypted and analog at some point - you can capture it if you have the hardware and willingness to e.g. grab it at a LCD display ribbon. Not as good/convenient as decrypting it, but it is an option.