From the SWFObject documentation:
swfobject.getFlashPlayerVersion() Returns a JavaScript object containing the major version (major:Number), minor version (minor:Number) and release version (release:Number) of an installed Flash player. Please note that while Flash version numbers normally consist of major.minor.release.build, SWFObject only looks at the first 3 numbers, so both "WIN 9,0,18,0" (IE) or "Shockwave Flash 9 r18" (all other browsers) will translate to "9.0.18".
So what if I do want to know the buildnumber as well? For example: I want to have "18,0,0,209" instead of just "18,0,0"
The solutions that were discussed here and here did not show accurate results at all for me.