Basically, when the tires start to spin they grab and release rapidly, while the suspension flexes/releases tension at the same time, causing the tires to "hop" rapidly. This can cause a huge amount of stress to the suspension and driveline, not to mention being uncomfortable and reducing control.Is there video anywhere of wheel hop? What is it? I don't think I've ever experienced it...
Here is a really bad case of wheel hop.
Here is a less catastrophic, more typical case of wheel hop.