Prop shaft bent or motor misaligned?

[jj4smith]

Took the following video of my propeller shaft. You can see the packing nut is moving back and fourth. Wondering if anybody knows if this is a bent shaft or if something is just out of alignment. I feel no vibrations when driving.

http://youtu.be/04UMPxPQf-8

1995 Mastercraft Maristar 200 VRS