The Web Standards Project is wrong on SWFObject
As for SWFObject, it serves a purpose that I might have someday in the face of a tight deadline, relaxed project requirements, or a requirement for the most recent version of Flash. However, I’ve been through every line of SWFObject’s code and can state with confidence that while it obeys the letter of the W3C Recommendations, it totally disregards their spirit.
I must always be faced with tight deadlines and relaxed project requirements because I use SWFObject quite often.
So if we shouldn't use SWFObject, what is Ben's recommendation? Apparently, according to The Web Standards Project, we are supposed to use methods that embed SWF files using only the Object tag. If you feel that there's a distinct disconnect between this recommendation and your own experience of reality as a Flash developer, join the club! I'm not going to go into detail about why this is such a bad idea here as Geoff Stearns has already done a great job of responding on his blog post. I believe that the following quote from his post summarizes it best:
Using only the object tag to embed your plugin content (especially Flash content) is fucking stupid.
I highly recommend that you read Geoff's post and I have to say that I agree wholeheartedly with it both in letter and in spirit.