In the past, we've had many issues with trying to get iMovie for iPad to accept video from other cameras. We found a solution, as did many other sites, and even then, different methods worked for different people. We can't be sure how or why, but it was a huge mess. It was a huge, frustrating mess.
The good news is that there is now an easier way.
If you need to edit video on your iPad, check out Elgato Turbo.254HD
It's a video converter. It will cost you a bit, but it's much easier than going through all that other steps we had to do before.
Main benefit here is that you can convert your files while loading them from your camera, which makes it one step process.
1) Drag your video files into the window:
2) Check your conversion settings, and set audio to 44100khz.
You will be creating a custom setting by using the existing iPad settings as a template.
3) Now, you can simply convert. From now on, you won't have to adjust settings or dive into the additional menus. Just choose iPad 44100kHz.
The amount of time this has saved us is worth the price. Editing video on the iPad works very well for our workflow and we'd recommend it to anyone who uses their iPad for video editing on a daily basis and needs to import from an external camera.
It's nice enough to get the five stars from us: