The video needs to be in webm format to work embedded; convert it to that format and then add it to Anki.
See an example of how the card code should look in the Editor.
<video id="b4fb41fd-c74d-414d-8116-7e23d1e153dd" class="video-js anki-video" controls="true" preload="auto" style="max-width: 500px; max-height: 400px;"> <source src="0002-para_eu_dizer_que_te_amo,.webm" type="video/webm"> </video>
