As you probably know Adobe Flash Media Server comes with it's own apache2.2. Now this is ok but, as in my case, you might want to use Adobe FMS with the apache installation provided by your linux distro ( debian in my case ).
Now there are several reasons to do this: you might feel more confortable installing and setting up the apache from your linux distro, it's a lot easier to install php support and other features in to the default provided apache using apt-get or yum. If you were to use FMS's apache you had to install php by hand for example.
Setting up Adobe FMS with another apache is simple once you understand how things work. I'll be very brief here ( if you want a more detailed explanation read here http://help.adobe.com/en_US/FlashMediaServer/3.5_TechOverview/WS5b3ccc516d4fbf351e63e3d119ed944a1a-7ffa.html ).
When somebody wants to see a live broadcast or a video stream from your server it connects via http to your machine ( eg. http://www.example.com ) on port
80. He/she downloads a swf from your machine and the swf connects then to your machine on port 1935 ( the default RTMP port ) and creates a real time connection to your server.
Now when using a different Apache server, Adobe FMS should redirect incoming requests on port 80 to your own apache installation rather than it's own. Because
Adobe FMS listens on port 80 for HTTP and 1935 for RTMP your own apache has to listen to another port. In this case HTTP requests should proxied from port 80 to 8134 by FMS.
Flash Media Server has the option to proxy http requests to another port / machine. If you have your apache on another machine you don't need to change the default port for it. If the Apache resides on the same machine as the Adobe FMS you need to change the default port from 80 to 8134 like I explained before.
Enable proxy-ing in fms.ini -> HTTPPROXY.HOST =:8134 ( this proxy-ies incoming http requestso to the same machine on port 8134.)
Setup apache to listen on port 8134 and you're done.