I just recently found out about the extension - Draftback. Basically this extension allows you to see the life of a Google Doc - from start to finish and with all the revisions in between.
Here's how to get started -
1. Install Draftback from the Chrome Web Store and it will appear in the top right corner of your Chrome browser next to the Omnibox (It's a gray box with a D).
2. Open a Google Doc and and then click the Draftback button in your document.
3. Draftback will process the revisions. When it is complete, click View.
4. A new tab will open with the Draftback version of the document and it will begin playing automatically. You can pause it at anytime. You can also use the slide bar to increase or decrease the speed.
This is a great tool for teachers and students. Teachers and students can see document revisions to help better understand the student's writing process. Teachers can also see the total revisions in a document and what content was used to create it.
One final note - In order to use Draftback on a document, you have to have editing rights.