There is little understanding of power factor by the general public, the demo you saw was an example of an ideal case for savings. An electric motor that had it's power factor corrected to unity with an external capacitor. But most electrical loads are not so simple linear loads like a motor. Typically the current drawn is complex and certainly non-linear.
Quoting from http://en.wikipedia.org/wiki/Power_factor
"The power factor of an AC electric power system is defined as the ratio of the real power flowing to the load to the apparent power in the circuit, and is a dimensionless number between 0 and 1 (frequently expressed as a percentage, e.g. 0.5 pf = 50% pf). Real power is the capacity of the circuit for performing work in a particular time. Apparent power is the product of the current and voltage of the circuit. Due to energy stored in the load and returned to the source, or due to a non-linear load that distorts the wave shape of the current drawn from the source, the apparent power will be greater than the real power."
You really need to read the Wikipedia article to begin to have an understanding of what's going on. In a home the power factor measured at the service entrance will vary considerably, be non-linear, be non-predictable and would require active power electronics to correct to unity. But even if you had it so what? You don't get a lower electric cost for what is measured by your power meter. The power meter measures "real" power not the "non-work" power returned to the power company. So there would be no dollar savings. Perhaps the latest state of the art residential power meter does measure the power factor and could charge more or less based on the power factor. In Maryland it's not on the utility commissions approved residential "R" rate schedule.
Bottom line is unity power factor is a good thing. Good for the power company, good for the stability of your equipment, good for the county because it reduces the total amount of electric power that needs to be generated. But for electronic loads, like computers and TVs, it needs to be corrected by each device. The old wall wart transformers are especially bad. Collectively they consume lots of power. New energy efficiency standards will greatly improve them. But again your power meter doesn't measure the improvement.