Audiobus: Use your music apps together.
What is Audiobus? — Audiobus is an award-winning music app for iPhone and iPad which lets you use your other music apps together. Chain effects on your favourite synth, run the output of apps or Audio Units into an app like GarageBand or Loopy, or select a different audio interface output for each app. Route MIDI between apps — drive a synth from a MIDI sequencer, or add an arpeggiator to your MIDI keyboard — or sync with your external MIDI gear. And control your entire setup from a MIDI controller.Download on the App Store
Audiobus is the app that makes the rest of your setup better.
Screen record and video record at the same time?
I guess if Rolands x4 camera maker app would let you screen record on one of the devices it would be enough, but maybe there is an online service that lets you send a stream from two devices to it? So you can screen record on one and video record on the other?
Would be nice to stream like that