IPhone App: Download All Videos (Including YouTube) or Cache All Videos?

Do you know of any app that can download any video on any site so you can watch them offline? I know one app where you can easily download any video from the web and watch them later. It's in the App Store, but my issue with that is, is that it "Downloads." I'd prefer something that has unlimited storage/cloud saving, so I can cache any video from the web without using much of my iPhone's storage, which is only 8GB total.

Added (1). To answer your question, sinterklaas, I said so I can watch them offline, by caching them. Caching videos doesn't use as much storage, ans cloud storage means it's offline, just saved not on your phon's memory.

What's the point of using cloud storage when the videos are already on YouTube? You have to access the internet to access the cloud anyway. You probably have a computer, right? Why don't you download videos with the Clipconverter.cc website, import them into iTunes and copy them to your phone? If you get low on space, just replace old videos with some new ones and/or get rid of the ones you don't watch.