If you are getting into editing and like the convenience of editing on your iPhone or iPad. This works well if you are using video shot on your own device but what about if you want to use footage from another device? Well then you need to get it into your camera roll. iMovie may not be the only app that wants to access your camera roll to use the video you have there. So how do you get it there? Well you’re going to need iTunes. You will also need it to be in a compatible format which is ok if you shot it on another iPhone or iPad. You may need to convert it first using something like Final Cut Pro, Compressor, Premiere Pro, iMovie or Handbrake.
Here is a video that shows you how to copy video to your camera roll whether you are using Windows or a Mac. If you have a Mac you may want to put it in iPhoto first and have included that here too.