This implementation just returns the size of the current loaded movie. The test is also deliberately written to be loose on timings so that it likely won't see a partially loaded movie. (I don't want it to be a test of load events, so I just wait a few frames, rather than the correct way of waiting for `onLoadComplete`.)
Until we support streaming file loads, we can't faithfully support these properties. Still, it's better to have them, just in case.
David Wendt