A frequent question I am asked during iPad workshops is how to get video that is saved on a computer onto an iPad to be used in apps such as iMovie or Explain Everything. The question is usually driven by teachers and students wanting to know how to download videos hosted on YouTube and get them onto their iPad to include short clips of in their video projects. I'll leave the explanation of how to download YouTube videos to others (it is my understanding downloading videos is a violation of the YouTube TOS).
As a resource for those looking to transfer video to their iPad (camera roll) I created the graphic below.
While it is likely there are other solutions, I find that both Dropbox and Box provide a reasonable work around.