GIFs of D-O's movements

[kresty]

Tony Stockert took some of the video from the stage demonstration and stabilized it.  Interesting look at some of the motions.

Looking

D-O (Dio) "Look" motion

And Nodding

D-O Nodding

I thought it was interesting how the linkage is used to keep the head level in the "looking" mode and used by itself to "nod".  Probably a good idea to keep the system in balance for those motions so he doesn't move when just looking and nodding.  (Keep the head's neck centered and the system appropriately counterweighted.)

And Turning:

D-O Turning

Turning is very interesting.  It's really hard (like impossible) to see in the original video AFAICT, but in Tony's clip you can see that between the tire and the outer edges there's a "ring".  The current supposition is that it's actually driving on those two "wheels" in tank mode.  These drive wheels also help keep it from falling over.  For this to work, the tire has to be soft or allow the treads to slide up when weighted.

Another possibility is that these wheels aren't driven and are allowed to freewheel, only being used for support. That hypothesis then suggests a flywheel type mechanism as the builders would've been familiar with BB-8's system.