anchor said that he ` made eye contact ' with egyptian government soldier on horse when the tahrir square protests became violent .
williams told jon stewart that soldier then beat protesters with whip .
doubts raised about whether he was actually on the square in early 2011 .
his dispatches from the time of the uprising were done at balcony above it .
nbc committee investigating williams is reportedly looking at the incident .
review of his reporting continues after iraq experiences were inflated .