I've got the exact same problem with video from Dailymotion as this post (https://www.joomlacontenteditor.net/support/forum/104372-cannot-insert-a-dailymotion-video
The others as Youtube / Vimeo, work fine.
I've also have this error in the dev console (Firefox) : Uncaught TypeError: k is undefined
Thank you for your response,
Charlotte from C3rb
Joomla version : 3.9.8
JCE editor Pro version : 2.9.16