One of the frequent complaints I hear is that a YouTube video imbedded in a blog post does not appear in the blog's RSS feed. This is also true for the 'Subscribe via Email' facilities found on most blogs.
The sad truth is that RSS is not a multimedia protocol.
For our own clients, we have a routine we have written that detects when the WordPress function the_content() is being used for an RSS feed. It scans the post and replaces the embedded YouTube video with an image. The image is linked back to the blog post.
The result is that RSS feed consumers wil see the image, click on it, and view the video in the original blog.