re: Poker & whats up with pokerstars
I haven't seen Beating Vegas, but there is such a thing as a truly random number generator for computers - for example, there's one that uses radioactive decay counts for a seed.
Older systems would have a less random number generator - for example the random number generator shipped with most programming languages is nowhere near good enough for real-money games.
Look back far enough in the mechanised/computerised gambling systems (e.g. old horse-racing machines), and you can find examples of ones which just had a long (say 4-hour) loop of results that they went through, so you could just watch one of them for long enough to know the exact result that would happen every time, but that gives no indication of the randomness of modern systems.
Besides, a normal dealers shuffle isn't perfect either - the randomness in most online games is likely to be better than that resulting from the average dealers shuffling.