else if in django template
Your {% elif %} in {% if my video...%} doesn't have any condition.
I think you should have {% else %} instead?
{% if my_video %}//if that url is an link to video
<img src="{{ my_video.thumbnail }}" class="img-rounded" alt="" height="75" width="75"/>
{% else %} //if that url isn't a video
<img src="{{post.image}}" class="img-rounded" alt=" EBAGU" height="75" width="75"/>
{% endif %}