OK… let me more precise. 😉
It can take a verrry long time, especially if you are doing an entire feature. It is recreating all the frames in the effect on a pixel per pixel basis and first goes through an analysis phase then the render phase. But it is end up being a true progressive source with 2:3 puilldown as though you had shot 24fps and transferred to NTSC. I use the FluidMotion to retime interlace materials as a frame converter to other frames rates – like adding a shot that was done interlace into a progressive project.
There are other solutions out there that would work as well – I was suggesting the one that came with the system so it was not extra $$ out of your pocket – just minutes/hours off your life… Look at Magic Bullet, Boris FX, DV Filmmaker, etc.
Michael
anything 24fps