The original purpose of the CB script was to read tips, and send them to the chrome web console. It was kind of a clever hack. They didn't need to program the chrome plugin to read chat. All they had to do was program the plugin to read chrome console.
I haven't checked in a while, so it may or may not do this anymore.
But the nice thing about reading chrome web console is that any site could add support by simply making their chat client print to web console. Which is usually as simple as adding one line of code.
Mostly CB scripting is very customize-able, interactive, window dressing. You can see in the script you linked to, they've added goals. Setting custom colors. Custom tip level messages. Messages that rotate.
If you look at all the different CB scripts that are out there, there is some real verity...