Simple "blur gradient" effect

sorry for what i’m sure is gonna be an easy question to answer, but i’ve wondered how the following look is made…

https://www.amadeodecada.com/Secure.html

specifically, just the background where the visible area fade into the dark background - is this done in solely in flash, or a combo of programs??

as i look at it again, it seems to be done in photoshop - radial blur - and just placed on the stage as a jpg or gif…or png…am i correct here??