The new version of vBulletin features a video embedding function. it allows you to insert a video (for example from YT) into your post directly by clicking on the following symbol: or just putting [ video ] and [ /video ] (without the spaces) around the URL of the video.

Supported videos include:
Hulu YouTube (Long) YouTube (Short) Vimeo Dailymotion Metacafe Google facebook


Here's an example video that shows how it's basically done and you can also just copy the video address out of the address bar at the top of the screen.