I can confidently say now that I speak Chinese. The road wasn't easy, and it took three years of hard work, as well as living in China for the entire period.  But now, I speak Mandarin fluently, and in some part this is thanks to YouTube.  Yes, being able to watch YouTube from China can help you learn Chinese.

How can watching YouTube from China teach you Chinese?

If you've learned a language before, or have started learning Chinese already, then you know that as a beginner, you just can't get people to speak slow enough for you.  When you speak to real people, in real life, there's just not enough time to catch EVERY SINGLE WORD, and you end up like the kid who learns how to swim by being thrown in the pool.  On top of this, most people don't have the patience to say something over and over again, in the exact same way.  And just to add fuel to the fire, Chinese people don't have a problem laughing at your poor Chinese (it's a cultural thing).

This is where being able to watch YouTube from China comes in.  You CAN make someone say something very slowly, and you can make them say it over and over again. There are tons of Chinese learning tools available for free on YouTube.  It's too bad YouTube is blocked in China though.

YouTube is great because there is a serious shortage of Chinese learning material in China.  Sure, there are some great multimedia resources out there for people interested in learning Chinese. But unless you're in a big city like Shanghai, Guangzhou, or Beijing, these things just aren't available.

YouKu is also a great resource for finding videos of Chinese people speaking, but there aren't a lot of "learning materials" there.  While you can find great examples of proper Beijing Chinese, and videos of young people speaking "real Chinese" as opposed to formal learning Chinese, there aren't always subtitles, and rarely have explanations in English.  All the more reason to get access to YouTube.

You're going to need a web based proxy or a virtual private network to watch YouTube from China.  These are both common tools to access blocked sites in countries that censor the internet. It will help you change your IP address, and unblock sites like Facebook, YouTube, Twitter, and anything else. VPNs will even get you access to Hulu and Netflix even though they don't stream to users outside The USA.