A bit late in the day, but I was introduced to
UMMY a year or two ago. Free download, downloads YouTube video and/or audio (MP4, MP3 etc) easily managed by a simpleton, can't recommend it highly enough. You launch a YouTube video, open UMMY and that video is selected already for download, you just select the format you want and download. As many as you like in one session.
PS I've just bought a new desktop, and after writing the above I went to download Ummy. I use Chrome, and for the 3rd/4th time in as many days Chrome blocked the software download, accusing it of being malware. It seems to me that Chrome now does this for any software that MS does not supply. So I tried to download Firefox, same result. So I opened Edge, and used that to download Firefox (no problem about malware!!) and used FF to download Ummy.
So, the usual MS-generated fury at their stupid antics, and a good laugh at defeating them so easily. I guess that Edge might well have allowed Ummy to download, so getting Firefox might have been unnecessary.
Is this a known problem with Microsoft and Chrome? Ummy has been downloaded 17m++ times, according to its website. I use a very good malware blocker and it allowed Ummy. I would believe anything of Microsoft.