MediaPlayerLauncher on WP7 - how to resume previously playing media?

I'm using a MediaPlayerLauncher to show movietrailers in my WP7 application, like this:

MediaPlayerLauncher mpl = new MediaPlayerLauncher();
mpl.Media = new Uri(trailerUrl, UriKind.Absolute);
mpl.Controls = MediaPlaybackControls.All;
mpl.Show();

This works just fine, except one thing: if the user is already listening to music in the background, and launch a trailer, the music is not resumed after the trailer is done playing (or if the user closes the video).

Does anyone know how i can resume the previously playing music/media, if even possible?