We've now added the ability to add up to one YouTube video to the end of your posts. There is a new field on the post page where you can enter the video ID for your YouTube video. You can find it in the URL line: http://www.youtube.com/watch?v=BK5n0yT5C1I
The ID is after ?v= in this case, the id is BK5n0yT5C1I. You can also paste in the entire URL, and the forums software will automatically strip out the video id from the URL. I've put a sample video on this post. Let us know if you have any problems.