If you don't log in, every time you want to download a file you are forced to fill out a captcha. If you are logged in, you still have to fill in a captcha, however not as often. My petition is to instead use Google's invisible reCAPTCHA, which can be programmed to automatically check using Google's system by simply clicking on any button. This will reduce the annoyances of a traditional captcha, and make it better for users.