post-grid.html

<article class="tile" itemscope itemtype="http://schema.org/Article">
  <a href="{{ site.url }}{{ site.baseurl }}{{ post.url }}" title="{{ post.title }}" class="post-teaser">
    {% if post.video.teaser %}
        <video width="180" height="110" autoplay loop>
        <source src="{{ site.url }}{{ site.baseurl }}/videos/{{ post.video.teaser }}" type="video/mp4">
        Your browser does not support the video tag.
        </video>

    {% elsif post.image.teaser && post.video.teaser == false %}
          <img src="{{ site.url }}{{ site.baseurl }}/images/{{ post.image.teaser }}" alt="teaser" itemprop="image" width="180" height="110" />
    {% else %}
    <h3>else</h3>
        <img src="{{ site.url }}{{ site.baseurl }}/images/{{ site.teaser }}" alt="teaser" itemprop="image" width="180" height="110" />
    {% endif %}</a>

   <h2 class="post-title" itemprop="name"><a href="{{ site.url }}{{ site.baseurl }}{{ post.url }}">{{ post.title }}</a></h2>
  <p class="post-excerpt" itemprop="description">{{ post.excerpt | strip_html | truncate: 160 }}</p>
</article><!-- /.tile -->