If it's just a static image linking to a landing page or something with a video, I don't see why it would have a negative impact. Deliverability won't really be affected by the content behind links, because it doesn't know what's there. The being said, do NOT use link shorteners in an email, if you were at all considering that. Those will most definitely hurt your deliverability.
Additionally, I follow the theory that you design your email as if images will not be enabled. So if you can get away without using an image, or you can supplement it with non-image elements, that's a good practice to follow.
All great advice, thank you all! Would you say the best way to include videos in emails is to include an image with a play icon that links to a video on a landing page? Or is there a better, more effective approach?