Users of my AudioStretch app sometimes ask me whether you can use YouTube content in it, for example to work out how to play a solo from some jazz concert video. Short answer: you can’t. AudioStretch doesn’t have the ability to grab content directly from YouTube, and even if it were technically possible to add such a feature, it’s probably not allowed.
That said, there are services to download content from YouTube and get it into audio or video files on your PC (or Mac). Once you’ve got the file on your PC, you can copy it into Dropbox. Then in Dropbox on your iPad, you can choose the file and ‘export’ it to AudioStrech (or other app) via the iOS “Open In…” mechanism. So here are a couple of services you can check out.
YouTube-mp3.org lets you download the audio track of a YouTube video as an mp3 file. Just take the URL from YouTube, copy/paste it into YouTube-mp3.org, and in a few seconds an mp3 will be ready for download.
If you want to download a video (not just the audio) from YouTube, go to the YouTube video, then change the start of the URL from http://www.youtube.com to ssyoutube.com, e.g. change:
That second link redirects to http://en.savefrom.net, and from there you’ll be able to download the video as an mp4. Note that you can you can open the audio track mp4 videos in AudioStretch via “Open In…” from Dropbox, just as you would load up mp3 files.
Disclaimer: I’m unsure of the legality of the above services, and have no idea whether they’re entirely safe, etc. so use them at your own risk! And also, please remember that much material on YouTube is not in the public domain, and probably shouldn’t have been uploaded to YouTube in the first place. If you’re just downloading a song to work it out in AudioStretch or some other time-stretching app, and not redistributing it, that may be OK (at least morally, if not legally). But if you really like a song, support the artist by buying a copy of it from a legitimate source. If your favourite artist puts out educational videos or books for learning their stuff, buy them. You’d be surprised how little most recording artists earn (and most app developers, for that matter). Musicians and other creative people often love doing what they do, but need to buy food and pay the rent too!