Dont hit PHP file

I'm not sure I get it either - but if you want flash to know and react according to the
current url (shown in the address bar) you could use FlashVars

If you are including your swf using the swfobject (http://code.google.com/p/swfobject/)
you can pass the url using the javascriot location object or you can pass it using php
(I'm not too much of a php expert - sorry)

Anyways create a flashvar* named "currentURL" (or whatever) and set the value to the current url
* Read more on flashvar here:
http://kb.adobe.com/selfservice/viewContent.do?externalId=tn_16417&sliceId=1

Inside flash the movie now holds a variable named currentURL with the value passes from html.
You can now make an evaluation of the url

switch(currentURL.toLowerCase()){
  case 'http://www.domainname.com' : trace('Do this'); break;
  case 'http://domainname.com' : trace('Do that'); break;                  
  default: trace('Do nothing'); break;                  
}

Hope this is what you are looking for

~ Jakob E