If you see a 302, something is doing a redirect, either a rewrite rule or a redirect in your code. Assuming "/admin/softwares/testupload" is a controller called Softwares with a method called testupload(), it should give you a 200, not a 302.
Yes, it is the session problem. Flash don't read the cookies info from the web as the session id is stored in cookies. Instead, it keep it's own set of cookies info.
The sample provided by Harro Verton (using Uploadify) has the JavaScript code to get the session info and attach to the Flash before submit.
I tried to search for solution how to attach the session id into SWFUpload and I get this:
swfu = new SWFUpload ({
... //some other settings
post_params: {
"<session_id_key>" : "<session_id>"
}
});
The session_id_key is set in the session.php depends on which driver is in used:
The Session driver needs to know what to look for in the posted data.
This is defined in your session config file. "post_cookie_name" most contain the post variable name that contains the cookie, in this case it should be set to "fuelcid".