This question is directed to Phil, In the Music Production with Motif Video, Scene 6. Applying Arpeggio's for inspirations, How do you play a different voice along with the drums?

Sorry, I don't have a copy of the video to refer to so I cannot tell you exactly what was going on in Scene 6 (I shot that more than two years ago - and I've never seen the finished video). But if you want to play along with drums this can be handled by placing the Drum Kit Voice and the Voice you want to play along with into PARTs.

PARTs are found in Performance mode, Song mode or Pattern mode.

Let's start by taking a look at a PERFORMANCE. A Performance allows you to play as many as four Voices simultaneously. You can play all four Voices yourself, or you can have an arpeggiator phrase "play" one or more of the Voices for you. There are four arpeggiator said available. There are over 7000 arpeggio phrases to choose from (more than 2300 of them Drum grooves). Call up one of the 512 factory Performances and take a look at how it is made.

This is described in detail in the Owner's Manual on pages 28-30: "Playing the Keyboard in the Performance Mode".

As it explains, in detail, you can select different Voices for each PART. And you can assign different Arpeggio phrases to the different Parts.
Try going through this short section, if you have specific questions post back here.

If you'd rather record your own drum groove, you can set the Voices you wish to use into PARTs of a Song or Pattern sequence setup.
You do so by selecting one of these two SEQUENCER modes, then by pressing [MIXING] > [EDIT] you can setup the Voices to the PARTs. This is covered in detail starting on page 37 of the Owner's Manual.

Thank you, your input is much appreciated!