Musical Brains released Beats TV. This is a video recording app with MIDI input to control video filters. It was designed with drummers in mind, but it is obviously not limited to that context. You could use it with anything sending MIDI. They even mention using Beats TV with Patterning in the iTunes description.
Beats TV is free to try, but to get rid of the huge Beat TV water mark in the corner you'll have to pay $5.
It is increasingly necessary for apps to release with videos. This is especially true for apps that are doing something unique and need to show off what sets them apart from the millions of other apps out there. In the case of an app that itself produces videos, it strikes me as pretty fucking lazy not to offer a demo.
Beats TV iTunes Description:V-Drum your own music videos! 20 reactive video filters respond to your MIDI drumming live as you play. Each kit piece (kick, snare, hats, cymbals, toms) controls a different aspect of the filter to generate beat synced visual effects. Mix in backing tracks from your iTunes library to jam to. Includes 7 sampled drum kits mapped to work with Roland’s TD-1 drum set, or use your own audio input.
INSTRUCTIONS FOR USE
1. Connect MIDI drum source (e.g. Roland TD-1 drum set, iOS MIDI apps, or DAW via network MIDI).
2. Select backing track, drum kit sounds, adjust mixer settings for optimum audio sweetness.
3. Press big red button to RECORD video.
4. Make your most melted rock star faces and lay down sick beats to generate funky video effects!
5. Press big red button to STOP and save to camera roll.
You can also connect other MIDI compatible iOS apps such as Patterning, or even a network MIDI session with your computer DAW e.g. Logic Pro X for detailed programming like selecting different filters with MIDI program change events. This way you can make a funner-than-usual video of your singing or instrumentals even if you don't play drums.
Note for TD-1 or other wired USB MIDI instruments you also need a USB to lighting connector such as the Apple Camera Connection Kit.