Since I had a difficult time registering and had to open Firefox to register, I am going to pester you with a bug report. I thought it was a clever scheme of showing a blank box, which meant don't type anything in.
I don't know about other webkit browsers, but the captcha does not work in Chrome because of the lack of APNG support. The main reason I believe though is because of the Portable Network Graphics group never accepted the proposed animated PNG and truthfully their isn't really one standard for it. Mozilla however has a definition of the standard which is widely accepted, but it isn't a real standard and isn't set in stone.
So basically what I am getting at, is APNG's don't work on all browsers. ;)
I don't know about other webkit browsers, but the captcha does not work in Chrome because of the lack of APNG support. The main reason I believe though is because of the Portable Network Graphics group never accepted the proposed animated PNG and truthfully their isn't really one standard for it. Mozilla however has a definition of the standard which is widely accepted, but it isn't a real standard and isn't set in stone.
So basically what I am getting at, is APNG's don't work on all browsers. ;)