Keep vertical line constant during playback

Hi,
I'm using the latest version of Muse Score on Mac with OS just before Lion. Anyway, when playing back, that vertical line always stops on longer notes, and I was wondering if there's a way to just keep it at constant speed as the notes play across. I'm trying to make some video lessons for my students, and I feel like it would help their sense that the beat stays constant all the time if that vertical line just kept going rather than stopping...

Thanks,
Blake