In my experience, transcoding with subtitles becomes an issue when the subtitles are burned in to the video. I often get external subtitles from https://www.opensubtitles.org/ and then stick the downloaded SRT file in the same folder as the movie. Make sure it has the exact same file name as the movie so jellyfin will associate the two together. Once I do that, it does not transcode at least for subtitle reasons.

Ty! Can confirm this worked for me as well.

I have playlist support now, but that’s all so far.

You’re ok, it’s a fair question. The initial want arose from my son asking me to download YT videos for him to watch offline, and the various youtube-dl, yt-dlp, pytube, etc based solutions all being in various stages of broken, due to how youtube always changes things on their end. I chose an underlying library (pytubefix) that seems to be fast in updating when YT breaks things. Nothing in my app is revolutionary on never seen before, except maybe the ability to choose and combine the exact stream you want, i’m not sure. I took everything I liked in various solutions and put them together to work how i wanted. Then I though maybe someone else might like it too, so i shared it :) I work on it when i want to and just kinda go in the direction i want.