QIs there any way to ask Quicktime, at the operating system level, whether any movies are currently playing?
AThis is not as simple as you might think. QuickTime is not a centralized system of movie playback. Each application that uses QuickTime independently creates and plays back movies from that application's own heap. An application may or may not use the QuickTime MovieController component; it may even use its own custom playback calls, completely (or partially) bypassing QuickTime's playback routines.
QuickTime is a set of utilities providing movie playback, not a single entity that plays back movies.