That video jogged my memory about one valuable tool I'd forgotten - "Fetch As Googlebot". This Webmaster Tools function lets a webmaster see if they've been hacked, especially when the hack also cloaks content and only shows it to googlebot.
There is a lot of this kind of cloaked hack going around for the past year, and it is very devious. Switching the user-agent in your browser to googlebot doesn't always reveal the cloak. This is because some cloaks also embed IP detection! This makes the "Fetch As Googlebot" utility a very helpful tool.