When posting a video on the site the correct way to do it is to get the "URL" from the video. On each video regardless of where you get it from there are two codes you can use; the "embed code" and the "URL" You want to copy the "URL"

Come to the forums after copying the URL and paste it in a new post.

Should look like this: http://www.youtube.com/watch?v=EzC7dmyK ... r_embedded

Then you want to highlight the URL and click the "video" button at the top under the subject.

Your URL will look like this:
And that will produce this..



Following these instruction should ensure you correctly post a video player into your post.