This is a service I would really like. There's also youtify[1], but neither work for me (with youtify Soundcloud works but not YouTube). The music simply never starts.
That's too bad because such a "music mode" is something I would love to see on YouTube. It's not that I constantly listen to music on YouTube, that would be a waste of bandwidth, but I use YouTube almost exclusively as a music/artist discovery platform, then I download the musics I like once and for all. But I would still appreciate a lot to be able to actually have a working playlist/queue feature on YouTube, and also to be able to desactivate the video display (and download) to only keep the sound.
It's too bad that hiding the video is against YouTube's TOS. Most of the time the video is a single static image anyway.
About your second point, I didn't ask for "letting users download the music or the video", when I said that I download the music it can be from many sources, most of the time .zip or .rar files that the artists put on mediafire or some services like this.
If Youtube doesn't work in Youtify, you probably have some sort of flash blocker installed. If you don't, a bug report would be appreciated. (https://github.com/youtify/youtify)
I don't have any flashblocker installed. I thought it was because of HTTPS Everywhere but I disabled it temporarily and got the same result. Anyway I won't add an exception rule to HTTPS Everywhere for YouTube. So I have no clue at all what the cause could be, I don't think a "it doesn't work for me" bug report would be of any help.
I made http://www.tunesicles.com . It allows you to easily search youtube (you can search for an album and instantly add all the songs to a playlist). Not sure if this is something like what you would like!
That's too bad because such a "music mode" is something I would love to see on YouTube. It's not that I constantly listen to music on YouTube, that would be a waste of bandwidth, but I use YouTube almost exclusively as a music/artist discovery platform, then I download the musics I like once and for all. But I would still appreciate a lot to be able to actually have a working playlist/queue feature on YouTube, and also to be able to desactivate the video display (and download) to only keep the sound.
[1] http://www.youtify.com/
EDIT: I guess the best service of this type I've seen yet is http://roll.io/ (which works for me on top of that). I was discussed on HN here: https://news.ycombinator.com/item?id=2665090