Now I have to ask one the question that I have been thinking about. I have interlaced and progressive footages in the same project. When I export the final project, do I use "lower" fields? :huh: If so, is it ok for progressive footages also?
Set "Lower Field" if you export NTSC project to be viewed on NTSC TVs or monitors.
Set "Upper Field" if you work on PAL project.
These settings will not mess your progressive footage, but will ensure (in most cases, unless there was some problem e.g. with capturing) that interlaced footage is handled correctly.
Set "No Fields (Progressive Scan)" if your project will be viewed on progressive displays. In most cases, it will be OK on interlaced displays also because majority of players can deal with that and output correct NTSC or PAL signal.