Confusion about movement states aside (and hey, my new suggestion of the moment is to call it a "movement transition"...), I just got done with some of my first multi-media implementation in Byond, and found it to be one of the simpler things I've worked on.

Coordinated animation and sound, no problem.

By the way, I found a reasonable collection of sounds at www.wavcentral.com. They have about 400 effects sounds, and I pretty quickly found just what I needed.