depending on your audio setup, you might want to avoid using the TTS in this command right before launching video in case it is causing your receiver to switch modes suddenly or creating some other conflict. Otherwise, the problems you are having probably have nothing to do with VoxCommando. I never had any problems when my setup was all analog, but with my digital receiver whenever it goes into a full digital mode (e.g. DTS) there are some complications with sound and TTS.
I can't use TTS when watching a movie with DTS sound, but it is fine with stereo music playing.