If you read the blog post it explains that it isn't so much that people aren't staying on your site, it's that the analytics code can't detect that they are still on your site say 5+ minutes later (watching a video) if they aren't clicking around. The javascript just helps report to analytics that the user is actually still on your site and hasn't bounced.
Another blog that goes into it, and links to the original blog by Brian Cray.
http://mindtheproduct.com/2011/08/da...ite-are-wrong/