Well, from what I can see that's not possible. The only DVDstyler that has ffmpeg 0.10.2 as a dependency is the old one (version 2.1). The new DVDstyler (version 2.3) does not list ffmpeg 0.10.2 as a dependency and would not ask for it period.
To make things simpler I'll move version 2.3 to extra and remove version 2.1 all together. That way all you should need to do is update, and testing will not need to be enabled. (Which I still think is were you are having your problem.)