When deinterlacing, make sure you eliminate the correct field.
You need to freeze the action in the last field played so you need to eliminate the first field on the frame.
If your movie is Upper First, the last field played is the lower, so in the freeze frame you need to get rid of the Upper field.
Is your movie is Lower first, you need to get rid of the Lower field.
This is not much important if the picture has no much movement, but in pictures with a lot of movement can show a noticeable jump.
rafael
http://www.nagavideo.com