Firstly I have to say that I avoid Youtube for pretty much anything except entertainment as it is a free for all and completely unregulated. It's also a money making enterprise that encourages outrageous claims, comments and activities designed to create more views and thus money for the creator.
Having said that, the idea that only performing the minimum amount of treatment based on age, quality of life and life expectancy is nothing new and has been around since the dawn of modern medicine. Someone in their 80's is far more likely to be offered palliative care than a radical medical procedure.
Given that PCa is a slow growing cancer, and that it is generally accepted that most men will die WITH PCa and not because of it - non-treatment is definitely an option in the older generation in order to maintain QUALITY of life in their final few years.
Now, you mentioned that this doctor was American and that adds another slant to it. Having lived in the US for 14 years, you develop an understanding of how the American health system works and the huge power, both financially and politically of the drug and medical care companies. The system works of action and procedures - not on let's wait and see. You are much more likely, regardless of age etc, to be offered a full set of procedures aimed at cure in the US than probably anywhere else simply because, for those that can pay and/or have the insurance, the medical resources are virtually unlimited.
The idea of getting a second and third opinion is also a stateside process - you might manage it under the NHS but you will probably be waiting a very long time.
You don't mention your age and where you live - both will influence what treatments are offered.