YouTube Comment Snob
When you're on the Web, you appreciate a little civility. Let's face it: Many YouTube comments are hardly literate, let alone civil. The YouTube Comment Snob, a Firefox extension, filters comments, hiding those that contain too many misspellings, excessive punctuation, or profanity. You can filter for ALL CAPS or no caps, too.
Note: This link takes you to Mozilla.org, where you can automatically install the file into your Firefox browser. The extension is free, but the developer asks for a $5 donation (which you can make at the download page).