limbo666/NowVideoDown ? reverse-engineered prompt

Build me a small Windows desktop app that makes it easy to download videos and audio from YouTube and other sites.

I want a simple window where I can paste a link, choose where to save it, pick the format and quality, then click Download. It should also support downloading just the audio in common formats like mp3 and m4a, plus batch downloads from a text file with one URL per line. It would be great if it could save profiles for different settings and folders, and switch between them quickly.

Please make it feel like a lightweight portable app, not something that needs an installer or admin rights. It should sit in the tray when minimized, show a small notification when a download finishes, and have a few simple theme options, including dark mode.

Use yt dlp and ffmpeg behind the scenes, and make it easy for the app to download or update those tools if they are missing. If you need to check current docs online while building it, go ahead.