At 60 meters every two seconds would equate to 1800 meters per minute which would equal 108 KPH
At 60 meters every one second would equate to 3600 meters per minute which would equal 180 KPH.
Now if you pay attention the telephone/electric/hydro poles are usually spaced at a distance of not farther that 70 meters apart, the norm is 60 so we use sixty in this instance. Some older places the poles where much closer together.
Having said that I looked at a number of different places throughout the video, and the numbers come up KPH not MPH, even grabbed the stop watch I know not very accurate but I checked it numerous times, I even went as far to find the length of the bike to check the distance in between the Poles in a couple places, and in those places with the distance traveled vs time it came out almost exactly the speed on the speedo in kph.
Later AJ