To Unblock youtube or anyother site you have to just Change your DNS servers settings
HOW TO CHANGE DNS SETTINGS
STEP BY STEP GUID FOR WINDOWS
DNS settings are specified in the TCP/IP Properties window for the selected network connection.
Example: Changing DNS server settings on Windows 7
- Go to the Control Panel.
Click Network and Internet > Network and Sharing Center > Change adapter settings.
- Select the connection for which you want to configure Google Public DNS. For example:
- To change the settings for a wireless connection,
(If you are prompted for an administrator password or confirmation, type the password or provide confirmation.)
- Select the Networking tab. Under This connection uses the following items,
- Select Use the following DNS server addresses. If there are any IP addresses listed in the Preferred DNS server or Alternate DNS server, write them down for future reference.
Replace those addresses with the IP addresses of the Google DNS servers:
For IPv4: 8.8.8.8 and/or 8.8.4.4.
For IPv6: 2001:4860:4860::8888 and/or 2001:4860:4860::8844.
- Restart the connection.
Test that your setup is working correctly; see Test your new settings below.Repeat the procedure for additional network connections you want to change.