ProFlightSimulator is FlightGear, a free flight sim that has been packaged up to save people the trouble of having to spend hours downloading everything that is included in the DVD set.

If you look halfway down the page that you have linked to, you'll find this :

Quote:


It's not all that bad, just remember, that you can get everything in ProFlightSimulator for free, and what you are actually paying for here, is the DVDs & the time you don't have to spend downloading everything.


If you'd like to "try before you buy" Simviation carries this Sim for Free download, as well as several nice addons for it.

http://simviation.com/1/browse-FlightGear-110-1

I have FlightGear running on my system,

here is a shot over San Fransisco to give you an idea of what you're getting:

You know what... I know about the flight gear forum but didn't relize these were the same program.

Many different people have taken FlightGear, and packaged it up under a different name, and are selling it.

FlightGear is OK with this, as long as the person selling it mentions what it is based on.

Flight Pro Sim, is another one doing this.

For the most part, any time you see a Flight sim being advertised, and it's not MSFS or Xplane, it's a version of FlightGear. 

I don't see much mention of Flight Gear.  Too me I would almost call this a fraud.  They might mention it somewhere in the fine print, but the lay person visiting that site would have no idea they could get the program somewhere else for free.