Why Doesn't the Launch Pad Burn Up?

[TopNotch]

Watch this unique view of a Falcon 9 rocket launch....

[Raydar]

That's an interesting vid. Looks like they sprayed... something, just before ignition. Hard to tell if it was water or CO2. (Think "fog machine".) Either would possibly have the capability of cooling things down. At least a bit.

Having said that, I don't remember hearing that the Saturn V (or Shuttle, for that matter) launch pad was severely damaged by the launch, but I'm sure it required an extensive refurb.

[Fierofool]

I recall seeing something once that referred to huge amounts of sea water that's pumped in at the moment of ignition and liftoff. 

[TopNotch]

It's water -- fresh, not sea water. Since SpaceX's goal is to eventually make the Falcon 9 rocket reusable, they don't want to spray anything corrosive onto the rocket engines.
BTW, the Falcon 9 was just certified by the Air Force for military launches (story here). So far, they have only been able to launch commercial satellites, re-supply missions to the space station, and two scientific satellites (one was for Canada). Their US competitor, United Launch Alliance, has had a monopoly on military missions until now. They also compete with the French Ariane 5 rocket and the Russian Proton rocket for commercial launches.