What no images? moving images?
For a thorough guide to markdown, check out cmark-gfm guide, which our markdown->html renderer is based on.
Images
Of-coarse you can include images in your posts! See this beautiful bear1:

And another bear having a bath2:

Videos
Here we will use html tag to embed the video, as markdown doesn’t (yet)
provides a way to handle it nicely. With the extra option :unsafe, our markdown->html renderer (markable) will let the raw html tags thru and
will not interfere. Here is one:
To get the code for embedding is easy, just go to the relevant video
on youtube, right-click the video and choose “<> Copy embed code”.
Then paste it on the .md file you are writing. Change the width and height attributes to your liking. Here is another video showcasing the original bear-blog: