It seems to be based on the old Chinese semiautomatics, where you just pulled/swung a handle back and it fired from a bottom-feeding magazine, small and not very efficient bolts, but to an attacking enemy, a few of these must have been bad news.
Around late eighties, I made an automated X-bow (Based on a Barnett brand frame) with top loading and a far stronger bow, mounted in a high cupboard and with an IR "cross" in the hall where bolts would be launched against when interrupted. Not small bolts like the one in the video, but regular modern bolts.
Well, I regained my senses and got over my paranoia (it was to clip anyone breaking in) and around the same time X-bows were banned in DK, as some dimwits were using them in a gang conflict and politicians allways go for the look-decisive approach and banned the lot (now you get a week in jail if you are found to be carrying a knife (even if it's blade is 2 cm) and if the blade locks open, you must be gangster *tsk-tsk*
Later on, I changed to stun mode by a Super Soaker shooting a saline solution with a HT connected to the muzzle. Never found a volunteer to test it on though.
The X-bow in the video has a very weak bow (perhaps to make a small motor able to draw it) as can be seen by the small bolts diving pretty fast when leaving the track and the fact that it loads and fires in one go, not only makes it slow (no good for hunting), but probably hard to hit with precision. Funny stuff nevertheless, but the video didn't have to be that long - I was expecting the guy to explain about it or something (I will never get the videos just showing the end result without any details).