Embedding a video directly is neither allowed nor advisable in an email. There are two main reasons why it is not such a good idea. Embedding video in the email increases the size of your email, and rendering them in your mobile or other devices can be really tough and bandwidth-consuming for your prospects

Major email clients, including Gmail, Yahoo, Outlook, don’t support embedded videos that play right there in the email due to security reasons and compatible reasons. Before the advent of HTML 5, web browsers did not have a uniform standard for defining embedded media files like video. However, very few email clients support HTML 5 and allow this behavior. The risk here is that even if your mail client supports embedded videos, there is a very good possibility that people you are sending this video to will be using a client that doesn’t allow this behavior.

Fortunately, there are some creative workarounds that Hippo Video offers to solve this problem. You can embed an animated GIF of your video (a 5-10 sec gif taken out from scenes of video) with a “click here to watch” CTA, or you can have a static image thumbnail with Play option, which will redirect to the video when clicked.