Movement disorder specialists DO say this video supports my argument. Since you can't answer any of my questions, despite you telling me to go get educated on the topic, I'll help you out and hopefully you'll learn something. This topic is old and misinformation is everywhere.

Parkinsonism is a blanket term used to encompass the family of diseases that have the four cardinal features of Parkinson's disease - the tremor, slow movements, rigidity, and postural instability. You don't have to have all of them, most people won't. There are many other associated symptoms of Parkinson's, but aren't the four cardinal features (REM sleep behavior disorder and loss of smell for example). Parkinson's Disease is just one disease in this family, but there are dozens more. Parkinson's Disease and the parkinsonisms are clinical diagnoses meaning there is no definitive test except autopsy, so the diagnosis is as good as the doctor who is stamping the diagnosis and the various tests that may be run to help support or dismiss the diagnosis.

Parkinsonisms from head trauma tend to not have the prominent tremor - they have more of the slow movements and rigidity. Think of Freddie Roach. Tremor usually isn't as prominent in most parkinsonisms where as the slowness and stiffness usually are. Also, most parkinsonisms are typically symmetrical. When you see Ali with a prominent asymmetrical tremor, you think Parkinson's disease, not pugilistic parkinsonism.