This is because as fast as light is -- moving at the speed of light -- it isn't instantaneous: at 299,792.458 kilometers per second (186,282 miles per second), it requires that length of time to ...

If you want the instantaneous speed according to the definition 2, that would also be 20 m/s. It's all about definitions. Suppose we want to have a discussion about gardening.

The wind “speed” is the 2-minute average wind velocity, while the wind “gust” is the highest instantaneous speed, and can be much higher.