It is not clear what you mean by "local TV." Local TV is television that it available free over the air to all viewers who have a tuner. It is also locally-produced cable content such as a local cable news channel or public access cable channel. The Mac application for viewing such programming is elgato's
eyeTV 3. Be mindful that the software must be combined with a tuner such as elgato's
eyetv 250 plus, which can receive all free broadcast and cable TV programming, whether analog or digital, in the US and Canada.