We installed JCE Pro and wanted to place Videos (not hosted on same page - simple https:// link) with <video></video>. After switching back from "Code" to "Editor" and back to "Code" it is replaced with <iframe>. 

For a short time i allowed the iframe option but changed it back to no. I was looking in the  Internet for settings to make it work but with no sucess yet. you may can help me out here. Screenshot attached. 

additional testing with different settings see attachment

also used standard editor / no editor just code and the <video> worked fine. then i switched back to JCE Pro and it changed again to <iframe>.

additional testing:

1. Switch to Code
2. write code
3. save and close
4. open again (will open direct in Code), no changes
5. switch to editor and close
6. open again (will open in Editor now) ,changed to iframe when checking in code
7. specialeffect: when type video code again, save, switch to editor and back to code it is iframe. but when press F5 w/o any save. it is again video

There is something weard happening between Code and Editor 

Code i used:
<video src="https://www.joomlacontenteditor.net/"></video>
and it changes to:
<p><iframe src="https://www.joomlacontenteditor.net/" sandbox=""></iframe></p>

the link is filled in from the page here, its just a video link - use any you want

Thank you for the feedback. After checking the release informations, we didn't install the update. 

• A Strict Media Embeds Option has been added to Media Support. Previously enabled by default, this option provides control over how media items are embedded (e.g., <video> for video files, <iframe> for YouTube).
• It is recommended to keep this option enabled for security reasons to ensure that media is embedded using the standard, secure HTML tag.

In our case the JCE Pro Editor could not identify our video source and did use iframe for it automaticly with the option Strict Media Embeds ON. 

Solution:

1. Turn Strict Media Embeds OFF.
2. We changed our surce so JCE Pro identify it correctly and uses <video> to keep  Strict Media Embeds ON.