If you want to set a video ringtone on your iPhone then you can easily do it with a Cydia tweak,VUZIQ.
VUZIQ for iOS is a Cydia tweak which you can download and install in your jailbroken iPhone.Download your favorite music videos and set them as ringtones for your incoming calls.
The app uses YouTube to search and download the video which you can use as your video ringtone for iPhone.The app requires Registration, the user interface has the home screen and video calls along with contacts and settings that you can choose via a button at the bottom of the app.Users can also edit video ringtones.
The app enables to connect to social networking sites like Facebook and Twitter and also to FaceTime calls through video settings.
VUZIQ is available in Cydia BigBoss repo for free.