Pay No Attention To That Man Behind The Curtain
Unless you are a software developer yourself, you probably don't think much about these mysterious creatures. However, developers are people too, and can find themselves getting screwed over just like the rest of us. Blurity is a utility for minimizing blur in digital images. The developer noticed a drop of in the number of installations actually completing. People would download the product, but apparently not finish installing it. Puzzling, and frustrating since those were potential lost sales.
The long and short of is that because this is a Windows product, many of the downloaders were using Internet Explorer (unlike the developer, because all us tech types know it's not cool to use IE). Recent versions of IE by default use a technology called SmartScreen which tries to help you avoid installing malware onto your computer, popping up warnings to alert you to possible problems.
In this case, through various unfortunate circumstances, SmartScreen was flagging the Blurity installer as something dodgy, and understandably causing people to abort the install. The developer had never noticed this behavior, because he typically used Firefox or Chrome as his browser. A rather rude reminder of what happens on the other side if the curtain...