Is the youtube video showing only wet surfaces? Because they seem way too reflective for airport pavement. I can understand when it is soaked, but otherwise, airport pavement is not reflective like that. It almost looks shiny.
The first part shows dry pavement but, the Time of the Day is late noon, which has been choosen to maximize the effect, because it would be otherwise very difficult to see, giving the low res and high level of compression on YouTube and on internet videos in general.
In any case, shinyness alone is not a property of wet surfaces, what gives the wet effect, is reflections. As you can see, in the first part, where there's no rain, there are no reflections, just the diffuse shine created by the low-angle of the sun over the pavement. With rain, shinyness goes down, and is replaced by reflections.
The effect is much toned down at different times of the day, but is still visible ( live on a PC, not on video ), and even if the shinyness is less, bump mapping will increase the perception of the small ground details, like pavement cracks, that would have been impossible to obtain just by regular texturing only, because they would always look flat, regardless of the resolution used.
And, what makes a lot of difference "live", at all times of the day, is the fact that the tarmac/concrete has shinyness, while the grass doesn't have any. This create the most realistic contrast, between the different surfaces, which will appear really "different", not just having different colors.
