@ Danfun128

Lack of source is not unusual for plug-ins. If it works, it works. BTW, note that CYS doesn't convert everything ... only what you want. In this case, if you select, it will convert a YouTube music video to a MP3 (or better) for your player without intermediate steps & extraneous files after download. Otherwise, your get just what YouTube has -- of course, the separate audio and video DASH files are stitched (no re-encoding) back together into a single file.

@ Molly

Interesting about youtube-dl. I've used some online services -- savefrom.net is one, but they don't do stitching w/o their app. (As a general rule, to limit 3rd party access to system & information, I don't use apps.) I'd prefer browser integration. CYS fills that bill very nicely, but only on newer OS's (FFmpeg's oldest compatibility seems to be Win-XP).