Out of the, like, 3 different youtube downloader solutions I've tried off-and-on over the last decade+, this is far and away the best one. Being able to download as MP3 straight from the extension would have been a godsend to 13yo me listening to 12 hours of BIONICLE fan podcasts a week on 250GB/month internet, and it's still immensely useful today for, say, preserving old stock music that's otherwise evaporated into history.