There is a post in the site updates area of the forum, but figured I'd make it more noticeable. Old youtube embeds should still work, though the videos will display larger. By default the video takes up the width of the post area. You can specify a width parameter to change that.
[youtube]{youtube link}[/youtube]
[youtube width=x height=y]{youtube link}[/youtube]
[yt]{youtube ID}[/yt]
[yt {parameters}]{youtube ID}[/yt]
[yt_user]{username}[/yt_user]
[yt_user {parameters}]{username}[/yt_user]
[yt_search]{search query}[/yt_search]
[yt_search {parameters}]{search query}[/yt_search]
Enjoy!