[mythtv] Fast-foward with DVB/ATSC recording not working at all speeds

[Endaf Jones]

In the last week or so something has broken fast-forward seeking of 
MPEG2 (ATSC) TS recordings from my DVB card.  PVR250 recordings appear 
to function correctly.

When I record PBS on AMC3 (Free To Air), I only see the preview of the 
fast-forward with the "3X" speed.  Any other speed and I see the 
progress bar move and the time increase but the video is fixed with the 
last image right before I starting fast-forwarding.

# Endaf