Very first impression, from a basis of hundreds of arm, shoulder and nuero exams, He's go a shoulder problem. Possibly Rotator cuff. No visible tremor at all, so without a better exam and a few other maneuvers, I'm not calling Parkinsons, so at this point that helping hand isn't to steady, but to push. Anybody can have a stiff shoulder at his age, or much younger. The ramp: I'm 71, former rock climber and Rescue. Used to be damn nimble on my feet. Now I am 71. You can be damn sure I am careful on the back ramp of my toy hauler, or any other unfamiliar ground. A reasonable prep person would have thrown some sand on the ramp so that moisture could not make it so slippery. His last few jogging steps off the end were sure footed and balanced.
I spent 25 years in the ER, and assessing gait was also a needed skill. He's pretty fit for an old man.