Try FCP 6 software down conversion. It should work with 720p25 to SD.
But I hope you don’t want to use this for mastering, just for preview!
Better quality is achieved by the Kona 3 or Kona LH, realtime hardware 720p50 to SD down-conversion. The 720p50 mode is used for 720p25 as 720p25 does not exist as a SDI signal.