Exported video does not line up with original in NTSC video.  I export portions of a video to do editing in other programs such as photoshop CS6 or VirtualDub.  I do all the editing using either uncompressed or Lagarith compressed so that I can do multiple passes without any degradation.  I have a detelecined an old movie  which is 1:06:46:22 long in Lagarith compression.  I exported from 20:02:01 to 40:06:00 in uncompressed format.  Both the original and the exported section have 23.976043 frame rate.  I used VLC to get the accurate frame rate as MEP displays only 4 digits.  The exported video lacked about 6 frames at the end.  When I imported it, it seemed to match the selection area, but of course the frames did not match up.  I managed to match up the frames by time compressing (time stretch) the end of the just imported video.  I was able to also import an edited version of the exported video, but again I had to time compress it to make it fit.  The edited version behaved just like the original export when I imported it, so the video information had not been changed by either Photoshop or VirtualDub.

I then tried to export the same selection as Lagarith compressed, but it gave the message "The export settings and the movie settings are different" and then said the frame rate for both was 23.98.  This time the exported video was missing only 1 frame at the end, but it needed time compression to make the original and imported frames line up.

I have not tried this with standard NTSC 29.97 frame rate files, as I must work with a detelecined version to be able to correctly edit the original movie.  I am restoring old films that have a family member in the cast.