There are two VideoPaks available:
-a version of the tombola sequencer from the OP-1
-a touchscreen XY pad that sends MIDI out via the OP-Z
Knob functions 1-4 are labeled on screen at startup, tap the "UI PAGE" text to see knob functions 5-8.
Tap the text again to go back to the first page.
XYpad sends MIDI CC to knobs 1 and 2, fader 1 sends MIDI CC to knob 3, and fader 2 sends MIDI CC to knob 4.
Knobs 7 and 8 control the gyro sensitivity.
Tap the top left corner of the screen to access the sensitivity values for the gyro.
I found them useful to have, but not very nice to look at, so they're hidden by default.
Due to a UI bug that I'm not sure how to fix, you have to tap the videopak name twice to exit.