They could just inject it inline. No problem there.

The whole document.write block 27-51 (possibly the CSS-block too, but I'm not sure about this) could be written far more elegant in jQuery.

But the real saving is that "drag and drop" code - jQuery would abstract all that isIE/isNS crap from them.

The block of code they injected here was 7.9 KB (3.7 KB gzipped). jQuery is 93 KB (33 KB gzipped). So no, I don't think that would have been more elegant. Injecting anything into users' pages without permission is insane. Injecting a huge library like jQuery would be even more insane.

As long as you're already injecting something, why not go all the way?

Wasted resources. The difference in size between the two (using the numbers from the above comment) is 85.1 KB. Now think of all the customers Comcast has and you will see quickly the difference it makes with a few KB.

Oh man, I thought you were being sarcastic earlier!?

...unless you're still being sarcastic?