Probs with AC3

I´m using a Nexus DVB-S-Card. With this card I can record for example mpg2 or pva streams within "normal" mpg-sound. With ProgDVB it is possible to record an extra stream in "AC3" (dolby digital). The BSPlayer can play the normal videostream and (if on HDD available) also the AC3-Stream (at the same time). But then the video only plays, I can´t slip to a videoscene of my choice. The only function I can get is the "Pause" and then I can play again. Do somebody know this problem? :roll: