Ah. Usually it's easier for us to give a useful response when we know what a user has tried and observed, as well as what the objective is. Since we would have to do the same thing as you to find out what an event is named, we're not likely to get a different result.
Regarding MB events generally:
In my limited experience with the various Media Browser clients so far, they each handle events differently and sometimes the events they generate will not be very usable because of their quirks.
For example, MB Classic apparently sometimes generates multiple MB3.Playback.Stopped events in a row when a music track ends in a playlist (or something like that).
An MB3.Playback.Stopped event is also generated when a movie stops, but it's important to note that this event basically seems to occur any time a track ends, so for example, if you watch movie previews before your main feature, when the preview ends MB Classic seems to generate MB3.Playback.Stopped event and then begins to play the main feature. So, it's probably not a very useful event if you *only* want it to trigger a command when a main feature ends.