I've been having a problem with rendering an MPEG-2 clip from a commercial DVD.

I cut the clip using VideoRedo. When I look at the properties in Vegas, everything is as I expect but it says it's progressive not interlaced. As you might expect, that leads to problems when it is rendered for DVDs. In the stills, everything is fine, but as soon as there is motion the scene gets blurry.

How could the video on a commercial DVD be progressive? I've looked at 6 other DVDs and they are all interlaced. Any ideas on how to render it to prevent my DVD authoring program from re-rendering it?