Android tv box

I know nothing about xbmc or Android TV boxes, but "super user" is an app which decides whether an app can use administrator privileges or not. If it is refusing such access then the correct thing to do is change that in superuser's settings, not to remove the superuser app. Curiously you need root (administrator) access to use this anyway, and on most androids you need root to remove pre-installed apps. So it sounds like your device is rooted, although it doesn't sound like you did that (or else you'd know what superuser was about).

If you now have xbmc running (using a different superuser app) but it isn't playing video that's probably a different problem, perhaps related to the version of xbmc you installed.

"Factory reset" won't help with your having removed the original xmbc. All that a factory reset does is delete user-installed apps and reset user-modified settings. It does not reinstall stuff that you have removed from the system; it can't - these devices don't waste space by keeping a second copy of the system software to restore from, so if you remove something there's no way a reset can restore it.

So, please bear in mind that I know nothing about this particular device, so can't give detailed suggestions. But to get it back to its original state, including the pre-installed version of xbmc, you'll need to find out how to download and reinstall the original software. Exactly how you do that depends on the manufacturer, so I can't provide instructions as I have no experience of these devices, but that's what you are looking for.

Otherwise you could see whether you can find a different version of xbmc from the one you installed, which is better compatible with your device.