If you happen to live in Las Vegas and have a TV with an ATSC 3.0 tuner, then, for the next few days, there will be a new channel on your TV. At first, the Roxi channel just appears to play music videos, but when you hit the pause button on your remote, the TV pauses — despite being a broadcast channel. There’s no DVR involved or app you need to download. And with the press of your remote, you can skip ahead to the next music video or even choose from other playlists, all within the…