Thanks for this! I could swear most websites are like 30% snappier now (and in fact the entire N900). I am thinking maybe flash is left on in the background, taking resources, even if I don't have a flash-enabled site open at a specific moment, because it feels like the entire experience is much snappier. I don't care so much about removing ads, but making Flash selectable on a per-swf-basis is absolute gold.

I realize this might be a placebo-effect, but everything has been good since I installed this filter. My battery even lasted a log longer. It might also be because almost every site I visit has some flash ad somewhere... I mostly read news on the N900 and what news site doesn't have flash banners these days?

What I'm not immediately clear about is how this works. How can you, using only css, "sniff" out swf:s that are included with swfobject.js, which is the "correct" way to include flash on websites these days? I guess I could just look at the app itself, but I haven't had the time.