[Enhancement] Fix the decrypt function - the decryption of the encrypted videos

[unixfox]

Currently, the decrypt function doesn't work anymore.

For example, encrypted age-restricted videos won't load anymore as we fetch them not through the special ANDROID user agent that allow to have decrypted URLs for all videos, but instead through the TVHTML5_SIMPLY_EMBEDDED_PLAYER agent.

[PrivacyDevel]

Here are some videos that seem to cause this bug: hc0ZDaAZQT0, 7a0qw5Ziqm8

The bug seems to currently affect some instances but not others. Here is a list of instances that are now able to play these videos but didn't use to: https://github.com/PrivacyDevel/DPR-addon/commit/c36b7a68ea5bea403b03cff2baad59a6a02029d7

It is also possible that one of these videos works on one instance but not the other one as well. The instances on this list manage to play both.

[PrivacyDevel]

Late update: some invidious instances may or may not play those videos. None of them managed to play them reliably over a longer period of time.

As far as I am aware only my Invidious instance is able to play them reliably because of the patch that I made so that it uses the Piped-Backend in the background to get its videoplayback urls.

[user234683]

Is it known why it's not working? I have the same decryption method implemented in youtube-local and I'm getting 403s even though parsing the function is working fine. What is yt-dlp doing differently? It doesn't seem to be the nsig decryption (I used --verbose in yt-dlp, took one of the decrypted URLS, undid the nsig decryption, and it still loaded for this decryption-required age restricted video: https://www.youtube.com/watch?v=fV4LHzN_ZKY)

[unixfox]

The decryption function is completely outdated, nowadays it's a big JavaScript file that need to be evaluated then the result is the decryption key.

Someone tried to push a fix here: https://github.com/iv-org/invidious/pull/2222