I think Captcha's were invented to ensure that humans, not machines (i.e., code), were processing web pages.
I have tried to download the Captcha image, but, limited success. It downloads something, but, not in a recognisable image format.
Either I am missing something, or the webpage is blocking the Captcha download.
Set two references, Tools=>References
Microsoft HTML Object Library (for the image variable)
Microsoft WinHttpServices version 5.1 (for the download function)