Using this service is the easiest thing in the world :-)
Firefox plugin: drag this link to your bookmarks bar: Get NoSpoiler Link. Then, when on YouTube, MetaCafé, etc. you can just click it to get an instant nospoiler link! :-)
Alternatively, use the textfield on the main page - and finally if you want to create the links manually here's how:
When on YouTube - just replace the www.youtube.com/watch?v=5LNbiczvC0g with nospoiler.com/y/5LNbiczvC0g.