Here's an example that I encountered a few days ago:
I only had an iPad (something more and more common, keep in mind their growing popularity) and wanted to download the Song "Alfur ut ur hol" by Björk (which you can't buy in record stores or the iTunes store - it's a rarity recording she released when she was 11 - but it's available on Youtube).
While there are youtube-downloading-apps on iOS, none of them were able to convert the downloaded movies into audio-only files.
Then I found youtube-mp3.org. The site, together with the iCab iOS web browser (which can download files) did the trick.
I only had an iPad (something more and more common, keep in mind their growing popularity) and wanted to download the Song "Alfur ut ur hol" by Björk (which you can't buy in record stores or the iTunes store - it's a rarity recording she released when she was 11 - but it's available on Youtube).
While there are youtube-downloading-apps on iOS, none of them were able to convert the downloaded movies into audio-only files.
Then I found youtube-mp3.org. The site, together with the iCab iOS web browser (which can download files) did the trick.