What history has he taught that is unprovable?
In reality the items were most likely stolen from a Jewish person around the 1800 mark--carved during the medieval period either in Spain or France, based upon the stone work-- and thrown away into the detritus trench near one of the much picked over Indian Mounds in the Ohio region of Indian mound earthworks.
The skull of the jewish person was discovered with the forehead phylactery still attached, and the remains were deemed recent--bured within thirty years of discover--based upon the condition of the remains and the lack of natural effects which would occur if the skeletal remains were two thousand years old. There was also forensic evidence reagrding the lettering system.
You can read about the controversy regarding these artifacts by googling 'The Newark Stones': look for the definitive explanation by Rachel Altman [ http://www.bibleinterp.com/articles/Altman_Newark.shtml ]
Dr. Altman's penetrating comment is: "If you found a US penny in a trench at a dig that was assumed to contain only ancient items, you wouldn't claim the penny to be a forgery when you saw it. First, however, you would have to recognize that it's a penny."
On his television show,he taught the Mormon history of American history.. even the LDS has been unable to verify this teaching of Joseph Smith with DNA ...