Besides the issues already raised in response, iMovie* does edit video 'PROPERLY', or at least up to the same standard as any other consumer video editor. You see all the video clips on your device, select portions of them and arrange them on a timeline, applying transitions if you like. See e.g. http://www.youtube.com/watch?v=MEaWuCrI24s . I'm sure you can grasp for a distinction from standard consumer desktop stuff but it'll be a post hoc effort.
Similar tools are available for audio and graphics retouching, similarly consumer focussed.
* and, yes, there's probably an Android equivalent though I lack the expertise properly to comment. Let's stick to the capability of tablets in general as the topic, shall we?