Sorry for the delay.
One option would be to use the HTML <video> element in your category description. So you would upload a mp4/webm or ogg video to your site then when writing your description click the source button on the text editor and use something like
<video>
<source src="catvideo.mp4" type="video/mp4">
Your browser does not support the video tag.
</video>
Only issue is you'd have to play around with adding some other html and styling to try and get the layout right. Alternatively you could add a button and have the video load in a pop-up modal.