Mine's even smaller:
<embed type='application/x-shockwave-flash' src='main.swf' width=760 height=424>
It's been tested on IE5+, all versions of FF, Netscape 6+, the version of IE for teh Mac, Konqueror, Safari (not sure what versions the screenshots that were sent to me are, presumably the latest), and Opera (same as Safari, I've got screen shots but I don't know what specifc versions so I presume the latest ones).
All in all, not including the browsers it either hasn't been tested on by me personally or the browsers that no one has sent me screen shots of, there's only a 3% POTENTIAL loss of visitors...and that's primarily with the assumption that it doesn't work in IE4...which it actually might, I just haven't found anyone with that browser yet who can test it for me.
It should also be noted though that you want to have a Flash detection script when the page loads, otherwise you're going to need to add the:
pluginspage='
http://www.macromedia.com/go/getflashplayer'
(thinkin you could make that even smaller using a tinyurl)
Also if you have transparencies that need to bleed over into the page you'll need to add:
wmode='transparent'
But that's it. Much smaller that those standards molesting luddites over at the B List and I think it might actually be even MORE cross browser and cross operating system compatible than their version...not that they're interested in cross compatability. You should always remember that places like the B List will ONLY slurp W3C RECOMMENDATIONS and they ALWAYS assume that if it passes W3C compliance that it MUST be cross compatible...which really couldn't be further from the truth.
I've actually been considering starting my own little group, based not on what I WISH was standard, but rathter based on what ACTUALLY IS standard by ACTUALLY TESTING METHODS on every single last browser and OS out there.