I get asked all the time what I use to blur out info on a screenshot. I use a great program called Greenshot. That blur feature users ask about is called, Obfuscate and is inside the Greenshot program editor. It has a wealth of other features! You can setup your own shortcut keys, edit the image, add a border, drop shadow, text, pointers and more.
I have created reports and guides while using Greenshot, reversed engineered malware notes, server takedowns, phishing campaign takedowns and user guides.
-jT