Megavideo Explicit How Do I Block A Specific Website?

How do I block a specific website? - megavideo explicit

I am using Mozilla Firefox. When I Megavideo.com opens another window with the original. The video does not contain explicit material desired. I want to block this particular site, but do not know how. For this help, I have Windows XP. Please help. Thanks for trying, and I hope that it will succeed.