It is not easy to find a good free proxy server. First try to search Google for example for "youtube proxy list", "free proxy servers list" or "unblock youtube". You will see some sites that offer free proxy server listings. We found these ones to be useful:

http://www.xroxy.com/proxylist.htm

http://hidemyass.com/proxy-list/

http://www.samair.ru/proxy/proxy-01.htm

However, it is more reliable to have a paid YouTube proxy. Here you can find some lists:

http://www.usaproxyserver.com/

https://getfoxyproxy.org

It is recommended to try United States and United Kingdom servers (try to avoid using German YouTube proxy as plenty YouTube videos are blocked in this country).

Open our software and click: Options... => Advanced.

Choose "Manual proxy configuration" from the drop-down menu. Then enter Address and Port.

Click "OK".