Depending on which version of swfobject, and which embed method you are using it may vary slightly, but in general a call to swfobject.embedSWF looks like this:
swfobject.embedSWF( "myMovie.swf",
"divIdToReplace",
"100%",
"900",
"9.0.0",
"expressInstall.swf",
flashvars, params, attributes
);
In this example I have set my width to 100% and my height to 900 pixels. If you are doing the embed in another way, post some code and perhaps I can help.
** NOTE **
Just because you can resize the container doesn't automatically mean you can "zoom out" on the swf. If the swf has "no scale" set, then instead of zooming out, you will just be cropping the swf.
** EDIT **
You can try setting the params object to include scale:"default", like this for example:
var params = {
menu: "false",
salign: "LT",
scale: "default",
quality: "high"
};
This is the params
object you would pass into embedSWF
like I have shown above.