I don't think you will be able to eliminate the iris effects on the video - thats why it works - it changes the picture.
Its a simpler system than, say, the Sony Ruby, which changes lots of things simultaneously (not the least of which is gamma / video levels) along with the iris.
In the Hitachi, its just basically the iris itself. Close it down, the picture (and black level) darkens. Open it up, the picture lightens.
I also think, based on my use of the unit, that "seeing" the iris do its thing is hugely dependent on what scene and what movie you are watching. When I saw it, I could rewind and watch and see the iris do the same thing every time.
If you calibrate black and white levels on your DVD player / TX200, you should see the iris open / close just like me or anybody else does, given the right scene.
As I said before, all the "tricks" and smoke and mirrors that these newer PJs (even the higher-end Ruby) are doing actually help 99.9% of the video you pipe through them. Is it worth it for a very rare observation of the system not working perfectly transparently ? I think in this case yes.
Plasmas do the same thing in many ways, Pioneer has "DRE", Panasonic doesn't even name it, and I'm sure the other players have their schemes, but the bottom line is that all of the effort is to give the picture a "better" (contrastier) look with the least amount of side effects. I can see the effects on EVERY one of these devices in my home, but I think all things considered, the approaches work very well.
I tried watching the TX200 with the auto iris "off" and the depth of picture and involvement just weren't there, compared to "auto 1". But there weren't any "side effects", other than the big one - very low contrast. Take your pick. I think at this price point the system works pretty well, but if you look you WILL see it - esp. if you are looking for it.
If you buy one of these, just enjoy it and don't look for it. I quit noticing it after a few movies.