Believe it or not, it is not easy watching the NFL preseason live. Most of the games are only available on local television, so if you live outside of the greater Kansas City area, you will be watching the game when NFL Network airs it on Thursday morning.
However, you can also buy NFL Gamepass through NFL.com for $99.99, which includes a ton of stuff including all of the preseason games streaming live. I made the purchase, and must tell you that it has been a disaster. The NFL has endured all kinds of problems getting the games live to its customers, and the customer service is laughably embarrassing.