There is a user who recently had his account deleted. This causes various things to run, in particular a down voted post gets deleted. When this down voted post is a question, it deletes the question and answers.
In this case, the post was about including youtube videos on the main site. While the post was down voted (disagreement), it shouldn't be deleted - its something that someone else will ask again in the future. It is better to have a record of the early policy decisions and questions asked than to have them disappear.
Please undelete the post. Suspecting this was going to happen, I +fav'ed it earlier so any user who can see deleted posts should be able to go to my favorites and see it with that red background. A mod could undelete it, or sufficient number of users with the undelete privilege (1k for beta sites) could do so. As its a deleted post, I can't really go there and flag it (I can't see it).