The whole music vs movie mode description may be a little bit outdated. In the past, many years ago, movies actually did not have very much deep bass content. Today, there is significant deep bass content in many movies.
So, to the extent that the music or movie program material doesn't have very much deep bass content below 30Hz, then one is generally best off running the VTF-1 in max output mode (ie. both ports open, and bass extension switch set to '2 port open' mode), and in other cases where there is significant deep bass content, then one is generally best off running the VTF-1 in max extension mode (ie. one port plugged).
Variable port tuning is the biggest difference between the STF-2 and VTF-1. There are some other differences though. The magnet on the VTF-1 woofer is stronger. Even with one port plugged, it can play a bit louder/cleaner in the deeper bass than the STF-2. Also, the frequency response of the VTF-1 is flatter. Finally, the finish quality is significantly improved on the VTF-1 compared to the STF-2.
Sincerely,