Is it possible to break a bearing during a rotor change?

I replaced my rear rotors + parking brakes + spring kit and all that good stuff. However, after pulling a stuck rear rotor off, it seems like something to do with the bearing may have broken.

The wheel now bends in and out and wobbles around like the wheel bearing was damaged. Not sure how this could have happened. Does anyone know what I should check? Not too pleased about this, and not really sure how this could have happened. My friend that was helping me with this DID hit the center axle nut a couple of times while trying to get the rotor off. I told him not to do this, however, I'm not sure this caused the problem.

Basically looking for some opinions on what I may have broken or done.

Thanks.
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Edit: Looks like it could have just been the axle nut being loose. Not sure HOW this came loose, as I didn't touch it, however, I have included some videos of before / after the new axle nut being installed. Doesn't seem to be shaking around much anymore. Hope this is all my problem was.

Wheel Shaking (showing signs of what I thought was a bad bearing:

http://www.designlabx.com/subaru/wheels ... shake1.avi

After replacing the Axle Nut (no more shaking / not much shaking):

http://www.designlabx.com/subaru/wheels ... shake2.avi