Don't be too hasty to dismiss John. He has an arguable point. Bart Sibrel made his first splash on pretending to have uncovered footage no one else had and misrepresenting its metadata (i.e., the "not for public distribution" slug) for his own benefit. I can certainly see others trying that same approach. While I haven't yet seen the calibration frames used in this way, it's not out of the question.
The vast majority of the Apollo footage people see are the convenience clips on YouTube and elsewhere, which are of course brief and/or edited excerpts containing the interesting bits. While the raw footage is ridiculously easy to get (e.g., from spacecraftfilms.com or directly from NASA's photo contractor), most people just don't look for it. So for the masses it would be easy for someone to say, "I have the rare, unreleased raw footage from NASA!" That's exactly what Sibrel did, and it worked very well for him.
And it wouldn't take much of a leap of faith to show the calibration chart and say, "See, this is what they do in studios. This proves it was shot in a studio." You bracket your chosen Apollo footage with scenes taken from Hollywood screen tests where equipment like calibration charts and clapboards can be seen. Not hard to argue it "looks like" that sort of footage.
I haven't seen anyone use the calibration frames this way, but it would be easy to do, and similar stunts have been successful before.