Viacom networks MTV, BET and CMT are giving an hour of free air time to President Obama less than three weeks before the midterm elections. The so-called “A Conversation with President Obama” will be live and commercial-free on six Viacom networks at 4 p.m. on Thursday. The networks will not give equal time to a Republican before the election, according to a spokeswoman. MTV denies that the Obama hour of TV is political, despite the timing, weeks before the midterm elections.