Playing interlaced material on a computer monitor looks bad, as anyone knows. Deinterlacing works, but camcorder footage may still have problems because it often contains fast pans that still look rattling and blurry at 25 or 30 fps.
Trying to find a way to send full quality CD copies of my DV footage to friends, I remembers those '2 x fps' filters in TMPGenc. Maybe making a full frame of each field would do the job.
It does !
Basically, it's a progressive, double frame rate format, an element of some HDTV standards.
On a CPU 800 MHz or above, MPEG2 at double frame rate can be perfectly played, and file size does not have to increase significantly.
I've added some text about it to my page, as well as templates for TMPGenc.