I would like to suggest an idea...
Great Software: only problem, it doesn't seem to work via proxy (I know I've entered all the details, It just wouldn't work in my university and to clear all confusion, university does not block youtube.com, also all known youtube downloader/link grabber works with proxy config, except 4K, which just wouldn't connect).
BTW, the University uses its own proxy tunnel/bypass whatever it is callled, to avoid its firewall blacklist.