PlayFullScreenMovie not pausing Unity on iOS

We are using PlayFullScreenMovie to play an intro video on mobile. On iPhone5S and iPad4 it is not pausing Unity playback and so the game is running in the background. On Android this pauses Unity playback until the video has finished (or the user taps to cancel). How do we make iOS pause playback as it says it should in the docs (and does on Android)? It is broken in both Unity 4.3.4 and 4.5.1.

The exact code we are using:

 Handheld.PlayFullScreenMovie("filename.mp4", Color.black, FullScreenMovieControlMode.CancelOnInput);

According to the docs it should pause Unity playback:

Calling this function will pause Unity during movie playback. When playback finishes Unity will resume.

From: http://docs.unity3d.com/ScriptReference/Handheld.PlayFullScreenMovie.html