From your video. It look like the Taskbar preview do not work. Try this, uninstall Start11, reboot immediately after. Check if Taskbar preview work while Start11 not install.
If yes, proceed to download and install latest Start11 version in your account product page. (V1.38 Beta) https://store.stardock.com/myaccount/products. Reboot immediately after the installation complete. Retest and report back.
If, no, Taskbar preview still don't work after Start11 uninstalled, check this https://www.thewindowsclub.com/tenable-or-disable-taskbar-thumbnail-preview-in-windows-10
Stardock Community Assistant.