Download Videos from YouTube, Vimeo or TED direct to iPhone (Not Jailbreak)
My mate who is an iOS Developer has created an app called Smart Tab Browser and this app downloads videos straight from YouTube, Vimeo or TED onto the iPhone.
He did tell me that you need to 'unlock' the app to allow it to do this, and he showed me how, basically there is a download window where you can type in a URL on the top Tab section, and in there you just write in Liberate and click on the download button. This then 'unlocks' the app to allow videos to be downloaded.
It is pretty cool, has a queue, so downloads multiple videos at once, has a backend file system that holds your videos in whatever folders you want. It also continues downloading the videos in the background, so start a download off and then play a game, and it is downloaded by the time you finish!
If you have any issues with getting it unlocked, just send an email to him from within the app,
By far the best way to download videos off YouTube, Vimeo or TED.