How do I save and retrieve CKEDITOR media (images and video) on a CDN?
Until CKEditor developers implement the functionality, you could create a custom module that:


on node add/edit you loop thru all fields using CKEditor and crawl each images/videos
detect if the images are already on the CDN
if not, upload the images/videos on the CDN
replace the images links with your new CDN links
save the node


I hope it will help you.