As per ACS Product description document, we can see that recommended maximum size of an Email is 60KB. Not sure, we can send more than 60kb size, but if the size of email is more than that or huge, then it may impact Email Deliverability.
Suggestion is, you can add a hyper link to watch the video or you can use an image (video screenshot) and provide URL to it, so that if a recipient click the image it will be redirected to your video.
Inserting a video directly into the email body is usually something done via widgets from Live Clicker (who we use) or Movable Ink. It does work, but there are downsides, such as the inability to make a video clickable to your website or to receive video view data to know how many users have watched a video. With the impending Apple privacy update, there may be impact on the use of video in email in Apple mail.