Code Impact from Dashboard Format Selection
By changing from Standard to Video format of the blog post we get the following three additions:
<body class="... single-format-video ...">
<div class="...format-video ...">
<span class="entry-format"> <a href="https://deepcoder.wordpress.com/type/video/" title="All Video posts">Video</a></span>
The first two additions are classes for extra CSS code. My theme does not seem to take advantage of this code, but if we customize this theme we will have a place to hang our CSS which will hopefully be portable across theme upgrades, changes, or WordPress.org upgrades.
The third addition is a button titled “All Video posts” to presumably bring up a page with all the Video format blog posts.