interlaced mode shoots differently than progressive.
interlaced mode captures the odd numbered fields first (field 1, 3, 5, 7, 9, etc) then captures the even number fields next (2, 4, 6, 8, 10, etc). It then assembles the fields together to make one full frame. Because it captures this way, it has to capture twice as many frames than progressive scan mode (explained below). since each frame only contains HALF of the fields necessary to make a full frame, the camera combines the two frames together (combining the odd and even fields) to make one frame, effectively halving the frame rate (from 60fps to 30fps).
Progressive mode (30p) captures differently. Instead of capturing the odd fields then the even fields and combining the two together to make one frame, it captures the fields in sequence (field 1, 2, 3, 4, 5, etc). This gives a much better image and this is how film cameras capture the image (progressively).
Ohh, and to shoot in 60i on the DVX100, go into the menu, and turn off Progressive mode. On my 100B, its Menu>Scene File>Progressive and set to off. Or, turn the camera to F1 (i think) and if you haven't made any changes, that should be 60i mode.
I understand almost everything about 60i except the capturing/editing part. If I am shooting a skate film in 24p and want some slowed down shots in 60i, how do I go about editing this on the timeline? Same timeline? 40%? Thanks guys.
Yes. Take the 60i footage you shot in slow it to 40% of it's speed on your 24p timeline.
This assumes your editor intelligently deinterlases and separates the fields turning them into frames.