Megastunts: Highwire Over Niagara Falls — Live! Friday, 9 p.m., Channel 5

The practice has been banned for over 125 years, but tonight, Nik Wallenda (above) takes a stroll from the US to Canada across Niagara Falls. It’s no doubt going to be a long 1,550 feet, during which Wallenda will be on a tightrope suspended 173 feet above Horseshoe Falls, the biggest of Niagara’s waterfalls. The highwire act, a Wallenda family tradition — Nik is a seventh-generation member of the famed circus daredevil clan — is part of a three-hour special that will include an hour devoted to the greatest stunts of all time.

Falling Skies Sunday, 9 p.m., TNT

Noah Wyle, his beard, and the 2d Mass return for season two of this alien invasion series from Steven Spielberg. Now that we know the “Skitters” aren’t the only creepy-crawlies, and their masters look as intimidating, it should get interesting. The best thing about this show, set in post-apocalyptic Boston but shot in present-day Toronto, may be flashes of humor within the grim reality. As Will Patton’s Weaver put it in season 1, “I don’t know what’s crazy anymore, we’re fighting aliens from outer space.” Pictured: Wyle (left) and Patton.

Let It Shine Friday, 8 p.m., Disney Channel

“Cyrano” with a hip-hop twist.

Fairly Legal Friday, 9 p.m., USA

A triangle loses one side.

StandUp in Stilettos Saturday, 10 p.m., TV Guide Network

Fall down laughing in flats.