Cute CUT is a fantastic free video editing and movie creation tool that, while it can feel a bit cramped on the iPhone's screen, offers a wide range of options. This is a great tool for stitching together clips in your library, adding short title cards to videos, or dropping a soundtrack into a video for sharing with friends. While much of what you're doing is possible and probably easier on a larger screen, it's impressive what the developers are able to squeeze into the iPhone's limited screen real estate.
After installation of the app, it will show you some basic tools for dragging and dropping in new clips. Periodically, as you edit, it will show you tips that can be double tapped to use a new feature you have not yet used. This allows you to drag and drop in new elements, draw on the video, record a new clip, and much more. Tap the "add media" button and you're given eight options of things you can add, some on your phone and others you can create in the app. Combined with a healthy editing menu for your clips, Cute CUT allows you to do a lot of things that you wouldn't be able to do on your phone with video, otherwise. The interface manages to make it all work fairly seamlessly, too, which makes editing fun, rather than a chore. The developers have also included video walk-throughs for using the app and when you share you can send videos directly to Facebook or YouTube.
If you are looking for a solid free video editing and movie creation app for your phone that will handle basic multitrack and multiclip editing, download Cute CUT. There are some more powerful tools out there, but this one is free and works very well considering what it offers.