I was just wondering whether there is a way to merely 'right click and add to list of videos to be downloaded and converted to mp3 immediately'. I'm obviously being very (!) picky here, but that's because I would like to find a way to easily collect and download quite a lot of music from Youtube embeds on music subreddits without actually having to go to Youtube or otherwise wasting a lot of time. The 'MP3 Convert' feature of it uses an external service which has been mentioned by someone else already, though:

There is already a Chrome extension called 'Ultimate Youtube Downloader' which simply adds a download button to any video page on Youtube, see here: