Here is an article on using video in email. --- http://www.email-marketing-reports.com/iland/2009/03/video-email-current-practices.html
This is becoming the most frequently asked question in this forum. Video cannot be embedded in email. It is not a limitation of Constant Contact, but rather a limitation of email clients. You can put an image in your email, and make a webpage that looks identical to your email with the exception that instead of the image it will have the real video. It sort of looks like clicking on the video in the email starts the video, but you are really transferred to the webpage with the video. There are a number of companies cropping up that can to this for you. You might also contact Tony Schaefer, Clique Marketing. I think he has experience doing this.
The only reliable way of adding movement is to use an animated GIF file. At this time embedded video in any email isn't supported in any mail clients. There are techniques that allow you to embed an image of your movie in your email. I posted an old draft of something I did for a client on Procrastinators message forum as this one is the pits for using any formatting. http://forum.eblastforum.com/viewtopic.php?f=2&t=20
The animated gifs have worked in virtually every email client. However, thank you Microsoft, they do not work in Outllok 2007. In my opionion the best alternative is the solution show in Tony's post.
After some testing, the Animated GIF did show the first frame in Outook so that would seem like a safe fallback.
To get video in an emaiil, you need to change the approach. We have sent many emails with Video, here's one we just did for "Burn the Floor" its really a fake front end to a link, but looks like a video panel: http://www.nytix.com/newsletter/2009/burnthefloor2/email.html
I use a screen capture of the video that is a hotlink to the file itself. I have seen increases in click through rates in the area of 30% when including a video.
You cannot embed objects (video, audio, flash, etc.) in email. This is not a limitation of Constant Contact. It is a restriction of email clients. This is one of, if not the, most frequently asked questions here. Just search this community and you will see the same answer as well as some alternatives. A frequently used alternative is to insert a picture of the beginning on the video and link it to the actual video. If you are not familiar with how to do this, I think that Tony (Clique Marketing) has done this for his clients and can help you with it.