Wanna use a video clip as a ringtone on your iPhone? You can with MiVTones from iFoneTec. Renamed from VideosTone To MiVTones, you can use its basic features for free, but you have to purchase a license to use MiVTones 2.0 with advanced features. Before installing the VideoTone application, you will first need to install the Dynamic Module Loader application. and activate your MiVTones Account at http://www.MiVTones.com and then install MiVTones from Cydia. Use http://app.ifonetec.com/cydia as a Cydia Source and find MiVTones.

You can then see the app settings under iPhone Settings, where you have to Enter your Username and password which you have registered at MiVTones.com. To upload your own videos you have to scp them to the folder /var/mobile/Media/VideoTone/Video on your iPhone.

Here is a video demo of MiVTones

Use iPhone mods and hacks at your own risk! Installing 3rd Party iPhone apps requires you to jailbreak the iPhone before installing the native software and apps. You can use Cydia to do this. Browse the full list of all iPhone and iPod touch native 3rd party apps filed under the software category.

More info here