The "listen to the letters" link brings up a small window which plays the audio version of the Captcha using the default audio player/helper app for the browser. For the vast majority of users this is going to be Windows Media Player. This only says 3/5ths of the letters before stopping. Only if following "Having problems hearing this? Try a direct link to it" to the direct link to the file, whereupon QuickTime Player is the handler (presumably only if installed) will the full audio actually be heard.
Also "request another image" just gives you the same letters but re-Captcha-ed. Is that intentional?
http://community.plus.net/forum/index.php?action=register
