For one, if they could make it work then it would be a fantastic use of space, which is your primary concern for public transport in heavily urbanised areas.Is it really a good use of space?
For one thing, it means all your roads have to have some huge overhead clearance, which stops you from having overpasses et cetera.
Secondly, your road has to be made wider to put the bus there anyway, since you need space for the bus wheels. I doubt that the extra half-lanes you need for the wheels on either side of the road will be much less than one full bus lane.
Thirdly, every bus stop, which was previously just a metal post sticking out of the concrete, is now a complicated two-storey structure with stairs.
And that's before we get to the problem with turning the damn thing. You'll notice that the video depicts this bus on an insanely wide road; I have difficulty imagining it in an area where space really is at a premium, and in such a place I can't imagine it'd really take up less space than, say, a dedicated bus lane.