Filmmaker, Dave Healy on the JFKresearch.com web site meticulously describes how easy it is to forge films using simple techniques used since the beginning of motion pictures: here how to perpetrate lie that JFK’s limo kept moving and didn’t stop...
Shift limo down to hide wheels and brake lights
Actual infield grass should get less and less as Main Street merges into Elm Street, but film forgers want you to think the grass continues in order to hide the limo wheels and brake lights