"The Trouble With Tribbles" (TOS)
Brand New Audio Commentary by David Gerrold
David Gerrold wrote the scripts for the original series' "The Trouble with Tribbles" and its sequel, the animated series' "More Tribbles, More Troubles",
"More Tribbles, More Troubles",
from Memory Alpha
episode was a sequel to David Gerrold's own TOS: "The Trouble with Tribbles". In his commentary for this episode on The Animated Series DVD, Gerrold states that the story for this episode was originally submitted for the third season of The Original Series, but third season producer Fred Freiberger rejected it. Freiberger disliked the comic tone of "The Trouble with Tribbles," and did not want to go down that road a second time.
This is pretty cool we get two commentaries from Gerrold about these 3 related Tribbles episodes (TOS, TAS, DS9) even though he only worked on 2. One in 2006 (TAS) and one recorded in 2009 (TOS).