Embedding a video can't work because it embeds an iframe, which is not supported
by most email clients for security reasons.
(What happens when Gmail shows embedded videos in displayed emails, is that you
send a link in the email body, and it is at rendering that Gmail adds the iframe
into the page.)
So the bugfix solution is to hide the button.
Since there is an option "res_model" that allows us to know when we are in that
case, we remove the video option.
opw 1905497
closesodoo/odoo#28911
len-odoo
264f89f63f