If it’s a youtube embed, the email default should be more reasonable. An html card with a bunch of embedded javascript isn’t going to work in email. Email clients won’t parse the javascript, so nothing will happen. There’s a recent thread discussing workarounds, but basically, you’ll want to make an image that’s a preview of the video (with a fake play button on it if desired), then make a link that goes either to your post itself or to the video source. That way when your users click it, something useful happens.
Related thread: Clicking in email re-directs to Youtube, not website - any work around? (not exactly your problem but some of the solutions are the same)