Is it possible to embed video into an email that will allow the viewer to watch the video within the email itself in a consistent and cross platform compatible manner?
Youtube videos can appear to be embedded when being accessed using GMail's web client, but no, it's email, there are effectively no content standards.
There is no method of embedding video in email that guarantees playback in all email clients.
The best current workaround is to use HTML5 video embedding, suggested in this blog post from Campaign Monitor. This allows you to specify a fallback image that prompts users of email clients without HTML5 video support to click through to a web page to see the video in their browser.
Here's the conclusion from their blog post:
HTML5 remains the best option for embedding video in email. Being able to reliably provide a fallback image is most certainly advantageous in non-Apple email clients - then for Apple users, the option of watching video in the inbox can potentially make for a unique and engaging experience.
Our recommendation remains that you should decide if it's worthwhile to send video email by referring to your email client reports first. If a high percentage of your subscribers are using Apple devices, then it could be a neat move. Other recipients will see the fallback image, which you can use to prompt click-throughs to a version of your video hosted online.
Here's their sample of the code you'd need to include:
<video width="600" poster="fallbackimage.png" controls autoplay> <source src="http://mydomain.com/video.mp4" type="video/mp4" /> <source src="http://mydomain.com/video.webm" type="video/webm" /> <source src="http://mydomain.com/video.ogv" type="video/ogg" /> <!-- Fallback if HTML5 video is not supported --> <a href="http://mydomain.com"><img border="0" src="fallbackimage.png" label="Fallback Image" width="600"></a> </video>
Sample taken from "HTML5 video in email: An update on client support for 2011" on the Campaign Monitor blog.