Hi Chris, the main tutorials like you're asking about are the ones at the top of the list on the resources page that Joe linked to above.

These ones:
http://moi3d.com/2.0/docs/tutorials.htm

Those go slowly step-by-step through the construction of a few simple models and contain additional explanation with a voice track too.

Those particular ones should work well for the kind of general introduction video that you're asking about.

Also the main help file is here (which includes those videos in the tutorials section):
http://moi3d.com/2.0/docs/moi_help.htm

The introduction section of the help file can be useful to read through as well, it's not too long but goes over the main concepts:
http://moi3d.com/2.0/docs/moi_introduction.htm

- Michael