So here's how it works: let's say I want to embed a clip of Aaron Curry absolutely dominating Clemson. What I do is find the URL of the YouTube clip:

Then I copy the part of the URL that comes after v=, and paste it in between youtube tags, like this:

After that, I click the post button, and I end up with an awesome embedded clip:

Embedding ESPN Clips

ESPN clips are embedded in a similar way. First, find the URL of the page on which the clip is displayed. Here's an example:

http://espn.go.com/video/clip?id=3893342

Copy the part of the URL that comes after id=, and paste it in between espn tags, like this:

[espn]3893342[/espn]

After that, click the post button, and you'll end up with something like this:

Embedding Hulu Clips

This one's a bit more complicated. First, find the clip you want to embed. On the upper left-hand corner of the clip, you'll see an 'Embed' button. Click on that, after which you'll be given a ton of code like this:

<object width="512" height="296"><param name="movie" value="http://www.hulu.com/embed/EZZFfvn6BuD8Jx-al3Q44Q"></param><param name="allowFullScreen" value="true"></param><embed src="http://www.hulu.com/embed/EZZFfvn6BuD8Jx-al3Q44Q" type="application/x-shockwave-flash" allowFullScreen="true" width="512" height="296"></embed></object>

Copy the part of the code that comes after http://www.hulu.com/embed/ and paste it in between hulu tags, like this:

[hulu]EZZFfvn6BuD8Jx-al3Q44Q[/hulu]

After that, click the post button, and you'll end up with something like this: