Has anyone successfully used Quicktime 6 Pro's MPEG-2 decoding capability to convert MPEG-2 video directly to MPEG-1 or lower bitrate MPEG-2?

I tried it briefly this morning but it seemed to work on the first few seconds of video then stop. I didn't have time then to investigate what was happening, but there seems to be some hope there. If MPEG-2 to MPEG-2 conversion is possible through Quicktime 6 Pro/Cleaner 5, the need to convert to MOV first will be totally eliminated.

FYI when I tried to convert MPEG-2 to MPEG-2 from within Quicktime 6 Pro itself, it gave an error similar to "there is no video stream found in this Quicktime file."