Tyrrrz/YoutubeDownloader ? reverse-engineered prompt

I want to build a desktop app that lets me download videos from YouTube. It should have a clean, simple graphical interface where I can paste a URL for a single video, a whole playlist, or even an entire channel. The app should then list all the videos and let me choose which ones to download. It would also be great if I could search for videos by keywords directly inside the app, instead of having to find the link first.

For each download, I need to be able to select the video quality and the format. For example, I might want a high-quality MP4 or just the audio track saved as an MP3 file. The app should automatically embed available subtitles and alternative language audio tracks. A key feature is allowing users to log in with their YouTube account to download private videos or content from their subscriptions. This needs to be a cross-platform application that works on Windows and macOS.