As a teenager, I remember watching the 1968 televised debates between Gore Vidal and William F. Buckley during the two national political conventions and thinking that they were way more entertaining than any of the TV dramas that were popular at the time. Those debates, unaccountably unavailable for the most part since then, have been resurrected as the centerpiece of the terrific documentary “Best of Enemies,” directed by Morgan Neville and Robert Gordon. The film positions those debates as a harbinger of the ideological sword-crossing that has become a staple of TV news. Except what we have now, as opposed...