Videos in the quality you choose, and whole playlists
The “Video quality” window shows each quality there is with its size, and “Sound only”. YouTube is supported, with a whole playlist or the videos you pick from it, and sound and picture are merged when they come apart.
The video tools are open source (yt-dlp, FFmpeg and QuickJS-NG), downloaded once when you agree. Zajil never gets around content protection: if a video is protected by DRM, it tells you so plainly.