WASHINGTON, Oct. 19 - The documentary that Sinclair Broadcast Group has instructed 40 of its television stations to feature in a broadcast on Friday night makes some of the most serious accusations against Senator John Kerry of the campaign. The accusations include that he single-handedly prolonged the Vietnam War, worsened the torture of prisoners of war and ultimately caused countless, needless deaths with his antiwar activism 30 years ago. The film is rife with out-of-context and incomplete quotations from Mr. Kerry and other antiwar veterans. Several historians said many accusations in it were not provable or stretched far beyond reality....