The ability to Restart a program while in progress is another new feature included with .
When you change to a live program that is currently in progress you may get a small pop-up near the bottom of the screen that says "Restart this program from the begining? ".
Click "OK" on that button and you will be taken to the start time of that program.
That pop-up message will only appear for around 5 seconds but if you miss it you can always restart by accessing the other program options. To access these options press "OK" or the select button on your remote while watching Live TV. This will bring up the Trick Play, Restart, Record and other options.
If you don't see a pop-up or an option to Restart from the program options, then that content is most likely restricted for Restart and/or Replay TV.