DDR/ps2
 

is the shaking from playing DDR(dance dance revolution)with the dance pad near the ps2 bad for the system?

I believe so, it's the force-feedback, no?

if you mean the shaking that occurs when you bounce and jump around on the mat and cause your tv cabinet that has your ps2 on top of it to shake, yes it does but it really depends if its like earthquake shaking or a feather landing on a flat surface type shaking. but most shaking is really not helpfull to your system.. for more info read you ps2 manuel