This really ought to be in the "Political controversies" forum, hopefully the moderators will move it there.
In US medical care is a 'middleman business' with all the nasty things that come with that. There are clients (patients), providers (doctors and hospitals) and the middlemen (insurance companies). Because of this middle layer things between clients and providers (patients and doctors) are not necessarily working according to the concepts of 'free market'. The only medical industry that cuts the middleman and works according to the free market is cosmetic surgery and dentistry. If you are in the market looking for a facelift you would approximately know how much money you'd need to save for that procedure and there is a healthy competition between the providers.
The big problem for me personally is that you will never know unfortunately, how much treating a major life threatening disease would end up costing to you. Facelift - optional, heart surgery and cancer treatments - are not. You can never prepare yourselves for the potential costs you may encounter in life if things get bad because you will never know how much money you need to stash away.
The point the movie is trying to bring is that you are not guaranteed coverage even if you are insured and with the 'wild wild west' of unregulated prices in the medical industry your entire life savings (easily hundreds of thousands of dollars) can be wiped out if someone in your family gets seriously sick especially long term. I don't have a hard time believing that medical bills is the number one reason why people go bankrupt (and these are the people who have healthy savings and are on the way to retirement).
Only multi-millionaires can feel truly 'insured' and comfortable with the state of our healthcare because they have enough money to cover outrageous costs. The truth is if you don't have all this money stashed away you are NEVER going to know if you will be covered. If you have a pre-existing condition, good luck getting insurance at all, you'd have to give up your dream of having your own business and go try to work for the boss (for the rest of your life), so that you can be covered under the group plan.
The insurance companies are 'for profit' businesses and they are naturally interested in collecting the premiums and paying out as little as possible. They train their personnel to maximize profits. Of course they pay the claims and many people get appropriate treatments, but there is no guarantee for you to know what will happen in your individual case. All the deceit and nastiness that comes with it that Michael Moore shows in his movie is not far removed from reality no matter how much he tried to hand-pick specific cases.
Healthcare in the US is uncontrolled and unpredictable that's the main problem here. There are some elements of the social care for the poor like Medicare, there are also hospitals where a homeless person or a low income uninsured person can receive free care (these places are mostly sponsored either by local governments, medical schools, or by the religious organizations). There are also hospitals that even insured people (if they don't have the right coverage) will be kicked out of regardless even if they are on the brink of dying.
There is another side of healthcare that many may not be aware of that I've personally encountered and that made me really worried. Each hospital negotiates a different price for the same procedure with different insurance companies. In addition, there is a different price if you are a cash patient (not insured). Imagine this scenario:
4 patients come to the hospital to undergo an exam using some standard equipment that's been around for decades.
1) patient 1 - uninsured 'cash' patient that can pay.
2) patient 2 - impoverished or low income uninsured patient
3) patient with a very high deductable using insurance A
4) patient with the same high deductable using insurance B
Guess what price each of these people will pay? They will all have to pay since 2 of them are uninsured and the rest two have very high deductables. The truth is you never know. Most likely each of these patients will end up having to pay a very different price sometimes the price difference can be almost 500%

. Patient 1 can be quoted something like 200-500 for the procedure. Patient 2 may be able to get it for free if he/she proves they are low income or get a significant discount and get it for let's say under 100 bucks. Patient 3 can pay 800 and Patient 4 may end up paying close to 1200. You think it doesn't make sense? I didn't know this at first until it actually happened to me.
There is no way for a regular patient (not someone involved in medical industry or an insider) to know what the 'real cost' of any given treatment will be. There is no 'real cost' the way the things are right now. There is no true social system or a true market driven system.