We just discovered a slight problem with the flashlog feature of the Flash Player. In order to be able to see traces from the flash players to the log file you are instructed to put the following lines in your mm.cfg file :

ErrorReportingEnable=1
TraceOutputFileEnable=1
This works fine, you see all your debug info, but DON'T leave it like that. Once you're done debugging, switch them back to 0. My colleagues left them for about 3 months and they got a wapping 3Gb flash log file. I was expecting some sort of limit from Flash Player, but it seems there is none.

So in case you notice the Application Data folder in windows is really taking up some space, consider looking over the flashlog.txt file.