Doesn't it just.
In case Apple hadn't noticed, OS X is primarily in use by Home Users. It's (generally) a great family OS. This absolutely *****, a MAJOR Home User feature that they promote heavily, and they can't be bothered making it work. They've known about the issue since the end of July and yet omit a fix from the first patch update.
Seemingly in 10.8.2 they are more interested in adding Facebook integration, if all media accounts are to be believed. Let's add more features and forget about making the existing ones work 😕
Incidentally, the specific youtube problem may have a semi-workaround. Instead of going to http://www.youtube.com, go to https://www.youtube.com and the page loads. I don't know if it works well enough yet to upload videos, but at least the main site displays.
What else is broken by this bug? How many other sites won't work? Who knows... if anyone has any tips on diagnosing what's going wrong, please let me know and I'll look into it further, there's no Console messages and the html for the page at youtube.com, according to Safari, is empty.