Include videos from S3 with Cloudfront in my blog articles

Using Django I created a blog, hosted on Heroku. The static files are hosted in AWS S3.
For now I’m creating and updating my articles in Django Admin, using CKEditor.
To insert images in my articles I use Cloudfront URLs (so they do not expire!), like this

<img class="img-fluid my-4" src="" />

so everything works smoothly.

But now I have to add videos stored on S3 (also using Cloudfront), so I tried this:

<video width="100%" controls>
  <source src="" type="video/mp4">

The video is displayed correctly on my blog, so everything seems to be fine, until I reopen my article in Admin, and I see in CKEditor the video tags being removed.
So what could be the right solution to add videos in the content of my blog articles?