... found the problem.
Sadly, Adobe's docs are quite remiss.
Adobe Edge Animate CC JavaScript API
...contains several typos in the code. When i cleaned up the Adobe docs code all is working well.
// Set a toggle to play or pause a video track
if (sym.$("testimonials")[0].paused) {
sym.$("testimonials")[0].play();
} else {
sym.$("testimonials")[0].pause();
}