Newsletter fails with video embedded

When I send a newsletter from a post where a video (YouTube) is embedded, it is not possible to scroll in the newsletter in my inbox. All I see (in Apple Mail and Mail on iPhone) is the beginning of the mail. All the content is there, but not scrollable.

When I select all text, and copy/paste it into a text editor, it says

and suggests to activate java script.

The preview of the newsletter in Ghost looks just fine — both in the desktop and mobile preview.

Any ideas how to fix this — maybe the video ought to be replaced by a thumbnail, that links to YouTube?