This is a UserScript (for use with Tampermonkey, Greasemonkey, or similar) which hides usernames and vote totals on the 2.0 version of LessWrong. Usernames are replaced with randomly colored bars. This makes threaded conversations easier to understand. Here's an example of what it looks like:
To install LessWrong v2.0 Anti-Kibitzer, first install Tampermonkey for your browser. Then click this link (which opens the .user.js script above) and follow Tampermonkey's prompts to install it.