Ok, well, it's been a couple weeks now and youtube.com is still down.
I think I've finally found out why.
Up until recently China's SARFT (State Administration of Radio Film and Television) only required that video sharing websites hold a license to be able to air their content in China.
Well recently, they have introduced some new regulations. From http://illuminantpartners.com/blog/index.php/tag/internet-china-chinese-online-video-sharing-sarft-law-regulation-intellectualproperty-ip-ipr/
"Under the new rules, all films, TV series, cartoons and documentaries must obtain offline broadcasting licenses before being transmitted via internet media"
Essentially, this is in an effort to stamp out pirated materials from being shown online. However, there is an exception in the "haven rule" which essentially says that for user-generated content (meaning stuff that individual people upload, not businesses) each piece of copyright-violating content will be removed upon notification.
Anyhow, because the youtube servers are not located in China, and thus they cannot enforce these rules, it seems perhaps the Chinese government is using it as an excuse to block youtube.
In any case, it means I will have to find some other way to get to see youtube content.