The problem is demonstrated in the video using kio-gdrive as Google Drive allows a foldername with a slash in the name. The same thing surely could also be done with other methods.

When a foldername contains a slash character eg "asd/fgh", Dolphin interprets the folder sometimes as "folder asd which contains the folder fgh" or "folder asd which contains the folder asd/fgh". Sometimes one happens, sometimes the other happens (can't reproduce when what happens exactly).

Reproducible: Always

Steps to Reproduce:
1. Create a folder which contains a slash "/" in its name (I used kio-gdrive, details about that in "Details")
2. Enter that folder with Dolphin and see it break

Actual Results:  
Dolphin interpreted the slash as a subfolder and handled it like that.

Expected Results:  
Dolphin should handle the slash as a character.

I can still open files which are in such a folder (example kio-gdrive), but I can't copy the folder to another directory with the error message "The file or folder /<emailadress>@gmail.com/dolphin_demo/Test/flash_folder does not exist."