Hi,

I am not too convinced of obfu, and not of decompilers either.
However, you will typically find people that know how to operate these beasts and have never seen a "mangle data" tool or heard about server sessions - and you will also find people who know how to deal with the server and communication side but do not know much about flash.
So by mixing elements of both, you will probably get rid of the amateurs. That is the level of adding random vars to the movie (so it decompiles differently every time) and expecting them back.
Now, there is another - perhaps simple - approach at cheating: load the original movie (including any protections it might have built in) and then - somehow - ask it to call its win function. The common "same origin" policy helps a lot against attacks - so think twice about crossdomain.xml files

Musicman