And just when you think there is nothing more to glean from YouTube, you change the scope of your search ... and ...

YouTube comes through with that 1st commentary track for Knick Knack (see Page 1). Previously, this was overlooked due to more narrow search terms. The new search brought up a YouTube with all the disc's commentaries. So Knick Knack's commentary was "hidden" within. They discuss the original 3D (stereographic) development and release. It starts @ 12min 50sec (automatically, as per link parameter) and ends @ 16min 19sec, here ..

YouTube:

Pixar Short Films Collection Vol. 1- Audio Commentaries [AUDIO]
[Knick Knack @ 12m50s to 16m19s]

(I'll update Page 1, too.)