Today I was working on a video player in AS3 that I wanted to be able to play any video on initial load by passing a variable through the query string. I had done this before in AS2 using the ExternalInterface class but wasn't sure if it was still valid in AS3. After a little quick research, I found that this is one thing that they left alone between the two versions.
So after a few minor AS2 to AS3 migrating, I now have an AS3 version of my QueryString class. The following app allows you to search through a query string for a value of a specified variable. To test, add a query string to the url and play.