4m wide is fine for four doors. If you are going for Origin doors, like in your video, they have a chart in their brochure that shows you the advised number of doors per width of opening.
I have an opening 3.5m wide and am going for 4 doors (3 would be cheaper, but I like the look of 4). I'm sooo having a traffic door (3+1). Useful for popping out with the washing, or for a breath of fresh air or to do the weeding or whatever. But you have alternative access to the garden so maybe you don't live in your house the same way I live in mine.
However, unless you have any reason (like PP) to have the doors fold out in only one direction, I'd still go for 3+1. Just much more practical for accessing the garden. Otherwise it becomes just a giant glass wall which you only open once or twice a year when warm enough.
Aside:
Why when people record videos, as above, do they not think about the sound? Distant and echo'y! Get a lapel mike, for goodness sake. Or a separate direction mike that you plug into the camera. This annoys me so much. More so than the whole thing being back lit and requiring an infill light so we can better see the gentleman in his nifty tie. Great demo videos, but 
the technicals
/end off topic rant