By Chris Hughes Chilling footage showing a youngMartin McGuinness setting up an IRA car bomb has been uncovered. It was recorded by a US film crew in Northern Ireland who were given extraordinary access to the Republican movement in the 70s. Parts of the film are now being shown on British screens for the first time in a BBC programme about the lost paramilitary documentary. The bomb McGuinness helped to prepare injured some 26 people when it went off in Derry’s Shipquay Street in 1972. The number plate of the car McGuinness was seen loading in the film was later found in blast debris. It is …