I think the set has to detect film in order to react.
Video won't trigger the 3/2 pulldown of 24 frames per second film sources.
I keep mine shut off. Some advertisements seem to judder a bit, but who cares?
I've heard somewhere that BluRay never needs correction, but that's hearsay.
On the same subject, I keep all the 120 and 240 and Aquomotion stuff turned off as well.
On a related subject, I just had a music DVD display severe video lag for the first time...