Command S not working at all?

This is a really weird one. It looks like you're getting some kind of video play setup. It might be the best thing to trash your illustrator preferences and hope that when the program goes back to its defaults that these surreal icons will be gone and you can once again save your documents the usual way.

To do so on a Mac:
The User Library folder in which Illustrator’s preferences are stored is hidden by default on most Macintoshes. To access it make sure that Illustrator is closed and click on the desktop to launch a Finder Window (Command-N).With this window in column view follow the path User>Home folder (it’s the folder with an icon that looks like a house—it may have the user’s name rather than “Home”) and click on the Home folder. With the Option Key pressed choose Library from the Finder Go Menu. “Library” will now appear within the Home folder. Within the Library folder find the folder called Preferences and within it find the folder called “Adobe Illustrator <Version #> Settings” (earlier versions of Illustrator might just say “Adobe Illustrator”) and the file called “com.adobe.Illustrator.plist” and delete both that folder and that file. When Illustrator is next launched it will create new preference files and the program will be restored to its defaults.

The advantage of manually deleting preference files in this manner is that after you’ve reset up the program (make sure that no document window is open) to your liking, you can create copies of your personalized “mint” preference files (make sure that you quit the program before copying them—that finalizes your customization) and use them in the future to replace any corrupt versions you may need to delete.

@kfregeolle That is a strange issue. I've tested just now with Illustrator and Photoshop and Ctrl/S in Windows 10 is saving normally, evidenced by the option to "revert" being grayed out afterwards. Is this pop-up box you're seeing related to tool tips or something? I can't seem to replicate getting that open. Is anything inadvertently checked in your Preferences > General tab? You can try (if you haven't already) to reset your preferences to see if that will clear out the issue. Let us know what else you've tried!