When describing various aspects of the Montage in-depth, most videos (including those of the estimable Blake) didn't go into much detail. It would be worth watching this detailed review of the MODX on Synthopia. As the MODX is the baby brother of the Montage, it has a lot in common with it. This video (which includes a time index of topics) covers a lot of this, such as FM programming, custom arpeggios and more.
Those of us new to the Montage and eager to dive into programming, this can be helpful.
Here's the link: Synthopia MODX review.