Today I learned that you can download YouTube videos and playlists directly to a Synology NAS using the Synology Download Station Chrome extension. The videos and playlist must be public or unlisted for this to work, which makes sense of course.
Videos are downloaded in
.mp4 format and are named based on the video title. If you’re downloading a playlist, all the individual videos are placed within a folder which takes the playlists name.
The few that I tested with are downloaded at 24fps with the resolution being the max available for that video. This 4K sample video downloaded at 2160p @ 23fps with 44kHz 125kbps audio.