Most NTSC set top players add a 7.5 IRE setup to your video, so it should look a little brighter. If you encoded your video with an black level of 0 IRE, then the set top player is actually playing back your video as it is supposed to be seen. If you encoded your video with black levels at 7.5 IRE, then your playback device is probably setting your black levels around 15 IRE, resulting in washed out blacks.
It is normal for DVD footage to play back brighter than DV footage. Here's a link to an excellent resource.
The cause of the noticable difference i see between the NTSC output from my little camcorder used as a D/A converter for monitoring and the NTSC output from the DVD player can indeed be attribued to the player 7.5 IRE setup.
I also found an another cullprit : my monitor has "DVD" and "other" options on component input image setup and it seems that the "DVD" setting is precisely there to compensate a source with 7.5 IRE setup and induce a sensible general brightness reduction.
Thanks Corey and Bob for your usefull input about this issue.