For example, say I own a site where the user has to log in to play games. When the page containing the game loads, it passes in a value into the game telling it who is logged in.
Then when the game runs, it can for example, load the current user's progress, or display "Welcome, IqAndreas!"
Actually all you need to do is use Flash variables, or FlashVars - That will allow you to take a variable from your database and plug it into the Flash file.
You can call a php script and use GET to post the variables and then retrieve them on the next page by calling another php script that retrieves the previous variables.