Refplace

A 2012 YouTube  video explaining Single Payer  Worth listening to if you have questions.
Another one, this  guy is politically active and has a progressive agenda but he explains things in a less academic way so is an easier listen.
And a more recent one from March 30

The main thing is insurance based Health Care is not working.
Americans pay significantly more for Health Care than other developed countries.  A lot of that is Administration and Bureaucracy the Insurance Companies put in to increase their profits.
Remember they are businesses and in it to make a profit.  So anytime they can avoid paying they will and they have set up a lot to do that.  For Americans that means less care at increased cost.