Megaupload is a popular file sharing host used for swapping files. Megaupload uses Captcha like many other sites for protection from automated bots. Users have to fill up the captcha before they can download the files, Captchas are good for avoiding bots but they are annoying for the user. If you use megaupload frequently to download files use this greasemonkey script which auto-fills the captcha for you.
The megaupload captcha is not the greatest, it only displays 3 characters and it is readable unlike Gmail complicated captchas. Using this greasemonkey script you can solve the megaupload captcha.
Download Megaupload auto-fill captcha script, you need to have Greasemonkey Firefox add-on to use this script