so, one should expect, there's no difference, how a file is processed, in iM or QTpro.. 

first is a screengrab of a red-green-interlaced, 1920x1080 aic encoded video.. 

color mainly greenish.. 

on Export from within QTpro, choosing 1280x720i, drops the green field:

plain red.. 

and, finally, Export of half the Original size, 960x540, i, results in a smaller (for this website all pics same size), but same color as Original.

We imported the regreen.video into iM09; created a New Project; added only that clip. 

Then, 3 Exports using QT, varying the size:

No#1: same size/res as Original = no difference to QTpro export

No#2: Exports using QT, size 12080x720, 

same effect as with QTpro: one field dropped!

but something has happened.. see below.. 

and, finally, a Exports using QT, half the original res, but NOT same color as Original nor as QTpro export..  a field was dropped.

You noticed it: the 720 export from QTpro and iM09 are both red-only, but diff. reds:

Pic not processed nor photoshopped!! .. plus, the real color would be that dirty greenish.. 

//to be continued//