When using an aerial or connecting cable TV without a set-top box, add a 16GB USB flash drive to your Roku TV and pause live digital broadcast television using Live TV Pause. If you forget to pause and miss an important scene, your Roku TV allows you to rewind and catch up.
How does it work?
Live TV Pause is only available on the Live TV input of your Roku TV and requires a dedicated USB 2.0 compatible flash drive with at least 16GB of storage for recording the video. As soon as you tune to a digital channel, Live TV Pause begins recording live television.
To pause the program, press the Play/Pause button 
on your Roku TV remote control. Even if you do not pause, you can press the Rewind button 
at any time to rewind the current channel up to 90 minutes, or to the point where you first tuned to that channel. When you tune to another channel, leave the Live TV input, or power off the TV, the place where you paused the program will be lost.
After being paused for 90 minutes, playback begins automatically.