iPhoneUtils is a set of simple utilities to perform some basic functions on the iOS device. There isn't much in iPhoneUtils, but it does provide functionality to determine if your application has been tampered with on the device, trigger vibration on the phone, and play movies.
There are two mechanisms for playing movies within iPhoneUtils: PlayMovie and PlayMovieURL.
PlayMovie will play content that is on the phone in the StreamingAssets folder. Given that you have limited resources to move content if you want to perform over the air (OTA) distribution, PlayMovie may not be of use to you. PlayMovie is best suited to game cut scenes and your initial game intro movie since these will generally not be long.
PlayMovieURL is more practical for long running movies, dynamic content that you want to deliver to the user (episodic), or content that is simply too large to reasonably be distributed within your application. Remember, these are still mobile devices and they have bandwidth constraints. If you make your app large enough that it cannot be downloaded over the air, you are placing a limitation on your possible audience and hurting your customer's experience.
While not the end all in determining whether or not someone has stolen your application, isApplicationGenuine provides a mechanism through which you can detect if the application has been tampered with. It won't catch every pirate out there, but it is a useful function. Don't depend on this function exclusively for combating piracy!