Attached is a spreadsheet of all the "cutscene" motions exposed in the SS2 motion database. These are the motions you can access via the signal response and conversation systems.

Spreadsheet includes the motion tag names, internal motion names, best guesses as to the meanings of the motion names ("humcpsch", WTF?), actor type intended to be used by each motion, number of frames, whether the motion changes the AI's location, and a general description of each motion.