When you need to tell someone about your YouTube creation, you can send a link - but it is cool to have the video ‘embedded’ in your email. The message will then display the ‘poster image’ of your video, and allow the recipient to just to click ‘play’.

Apple Mail does not normally allow you to compose an HTML mail message, but there is a workaround that allows you to embed a YouTube Video in an Apple Mail message.

Thanks to bytes.com for providing a lead on this.

Step One

Go to YouTube, locate the video you want to embed, and copy the text in the ‘Embed’ section on the top right of the page, as in this screenshot.

Step Two

Open the application TextEdit, create a New Document (File>New), and paste in the text you have copied from YouTube.
It will look something like this

1

<object width="425" height="344"><param name="movie" value="http://www.youtube.com/v/heoO_5MvZ0w&hl=en_US&fs=1&"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/heoO_5MvZ0w&hl=en_US&fs=1&" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="425" height="344"></embed></object>

Step Three

Change the format of this document using Format>Make Plain Text

Step Four

Save this document as message.html

Step Five

Open the newly saved document in Safari, by navigating to message.html using File > Open File…. (or Command-O)

Step Six

In Safari, select File > Mail Contents of this Page, or Command-I.
This will magically create a new message in Mail containing the embedded video.

Step Seven

Edit the message in Mail as you normally would, and then send it on its way.

(Addendum - this may not work in Mail 4.2 and you may need an extra step, as described in the comments below)