You have got to be kidding me!! You are watching the Pokerstars.net "The Big Game" and trying to learn proper poker procedures from THAT. You might as well be watching old reruns of Celebrity Poker and the like.
Andy you would learn more by watching play money cash games and/or tournaments on Pokerstars.net or most ANY other site than you are going to learn by watching this kind of ENTERTAINMENT. These shows are NOT intended to teach anyone anything about proper poker procedures. They are intended 100% for entertainment value and to draw new players to the sponsoring site PERIOD!!
In all my years playing cash poker, I have NEVER seen any one, not even the drunkest player or the most inexperienced, try to call a clock in a cash game. RRoP, Version 11, Section 14, Sub. 16 says:
16. In all no-limit and pot-limit games, the house has the right to place a maximum time limit for taking action on your hand. The clock may be put on someone by the dealer as directed by a floorperson, if a player requests it. If the clock is put on you when you are facing a bet, you will have one additional minute to act on your hand. You will have a ten-second warning, after which your hand is dead if you have not acted.
So it appears it is possible to use a clock in cash games, but again it would have to be specified in the local House Rules.
By the way, Tony G is a very good player, but he is not the stellar example of proper poker etiquette.