You will need to edit the actionscript file. Look for the name of the file that it is redirecting to in the code and then change it to fit your needs.

It's a copyrighted material so I cannot or would not edit it. I have to somehow negate the affect of the redirection.

I don't see how you can override the redirect if you do not modify the actionscript. The only way I could see that working is if you have control over the page that iredircts to. If you did then you could do a javascript redirect from there to the page that you wanted it to go to. Personally I would contact the person that gave you permission to use the file and ask for permission to modify the redirect.

if they permit you to add the flash on your site, mail again and tell them and get the premission to edit the redirect url .