Damn dude ... that video shakes so much, I couldn't see anything.
The service manual in the troubleshooting section reads as one of the symptons, "a pronounced hesitation or jerky movement during acceleration, deceleration, or sustained speed" ... and some of the cause might be ...
* Bearing damage (doesn't say which one)
*Improper gear lash.
* Gear tooth damage.
* Broken driveshaft.
* Broken gear teeth.
* Seizure due to lack of lube.
* Small foreign object lodged between the moving parts.
And that's it. Good Luck. Let us know what ya find out.
Later ...