Try reversing your clip. You could make a normal emitter, add a floor for the confetti to fall on, render the file and then play it in reverse in a new comp. This seems like the easiest way to do it anyway.
I don’t have an answer to your question but I have a question for you. What are you using to export to FLV from AE? I am running AE6.5 PRO on Mac OSX (tiger). I have tried to export to FLV but can’t find the option.
I don’t think there is just one particular plugin in use here. Trapcode and Knoll offer some plugins that will get you going in the right direction though.