No photopost did not write the flash uploader. Your referencing a php file that simply loads the flash code.
. Added support for Flash Uploader (disabled by default, not supported by PhotoPost, but be enabled)
In any of our release notes about the flash uploader being included we openly state we do not support flash code.
The point here is our written code and features we test and work on all server setups. We openingly support all our code and guarantee that it works as noted. Now users wanted the use of a flash uploader which meant including outside code we do not write. It is a known fact the flash uploader will not work on all servers and setups. Now we gave into customer pressure and included a flash uploader but we have explicitly stated we do not support code not released by us which is known to not work on all setups so we have included a switch to enable or disable it.