i think you removed the plasmoid showing the tasks in use but not sure, if you recorded this you moved too much the camera and i couldn't hear what you said
there was a way to kill the taskbar and create a new one, Texstar posted it but can't remember where, not sure if remove the one you have now and on the desktop right click/add panel/default panel
this will create a new panel with default settings so you will need to configure it to your needs
there is another way to do this, put a new plasma widget to control tasks, the one i use is called system tray but you can also add smooth task
to add it to the taskbar unlock widgets and left click on the cashew of the taskbar/add widget
drag and drop
sorry if this wasn't what you need but is all i could understand from your post and the video