I would appreciate it if we could embed YouTube clips to explain ideas and concepts, rather than linking them externally. It makes the explaining a little more interactive and less fragmented. I think some of the SE sites have this enabled but I don't think it's been done here.
We can certainly enable YouTube embedding assuming there is a need for it. Over on Movies & TV (a natural candidate for the feature), we asked the community to list posts that could benefit from embedding video. Because text searches (primarily via Google) provide much of the traffic to Stack Exchange sites, it's important that video supplement the content of posts. For instance, it probably makes sense to embed videos to provide visual evidence of the veracity of an answer that's already been fleshed out in words.
I looked at a few of the top voted post that link to YouTube and also some from the "most relevant" sort. From that sample I think enabling embedded videos would likely be beneficial here. Not all of those posts would need more than a link, but some would definitely look better on this site if the reader didn't have to follow a link to another page.
I'm planning to turn this on sometime next week unless there are any objections.