When would I use Deinterlace?

[Holomatrix]

Hi, just wondering when I would use deinterlace? I have an NTSC interlased DVD and have unchecked progressive in CCE and everything looks fine. So just wondering when I would use deinterlace and which one is the best.
Thanks

[Twin]

http://forum.vcdhelp.com/viewtopic.php?t=84792

[Holomatrix]

Thanks for the link. Here's a good one too.
http://www.geocities.com/lukesvideo

..basically I do not need to De-interlace the video if I'm going to watch the video on my TV, just uncheck the progressive option in CCE and if I find a movie that seems to be both Interlaced and Prograssive then I would use the Decomb Filter and encode as progressive. Right?

Thanks

[Holomatrix]

Change of plans.
Did some testing with different parts of my interlaced NTSC video and came to the conclusion that 'TELECIDE' de-interlace is needed to get the best picture. By not de-interlacing and unchecking progressive in CCE the video does not end up with horizontal interlaced lines but does make the video blurry when there is movement, and with all the de-interlaced options that give as clear a picture as possible on still shots with no horizontal interlaced lines, most crisp and no 'wierd' thick horizontal lines on diagonal parts like car windshields (Hard to explain), doing a TELECIDE de-interlace is the best. Now this conclusion is based on looking at the stills on my monitor and not on my TV but should still be OK.

If anyone else has done testing like this, could they please let me know what they have noticed?

Thanks