In case you don't know, you can embed the video in the email and keep the source file on your website. This way the email itself will be small. I'm not sure if you already ment this
Something you should look into a little more is what email clients would block your content. I've tried a number of ideas at Corel to embed swf etc. I found that some default settings in Outlook 2003 would block the content from being loaded into the email. Therefore you wouldn't get consistent performance in all recipients.
Steve