Andy, all the character animation was hand-drawn frame-by-frame in Flash (drawn on top of reference footage)... Certain elements were drawn as a few looping frames as a Flash asset and then keyframe animated relative to the characters (e.g. the main character's tie), but then the final Flash animations were composited with the background plates in After Effects--the "jitter/random movement" was achieved simply through the naturally-occurring inconsistencies in drawing every frame by hand (we're not real 2D animators, but we used that to our stylistic advantage :^)

Thanks for the comment!