.flv off a .swf file

how do you get the link of the .flv file played by a .swf file in a website?
(like what gametrailers does. I can get videos from youtube with a browser plugin, but on other websites its a different story)

Using Safari

1. Open the Activity window. It shows all objects the browser has loaded for each page.
2. Find the entry that says blahblah.flv. You'll recognize it because its size is measured in megabytes instead of kilobytes.
3. Alt-double-click it.

So simple even your mom could do it.