How to set cookie to only show intro animation once per session
You could try something like 

  {% set vidAlreadyPlayed = getSecureCookie('intro-animation') %}
        {% if not vidAlreadyPlayed %}
            {{ setSecureCookie('intro-animation', 'hey', now | date_modify("+60 seconds").timestamp ) }}
            &lt;h1&gt;No cookie set&lt;/h1&gt;
            &lt;!-- do your animation logic here --&gt;
        {% else %}
          &lt;!-- do something else --&gt;
          &lt;h1&gt;Cookie set already&lt;/h1&gt;
        {% endif %}