TBH when I was younger I used to keep my pony at a yard that has all the jumps in the fields.
No accidents ever happened but it does make you think..
It was considered normal to jump around all the other horses grazing - may think twice about it now though - strange what old age does to you!!
Depends on the space. I wouldn't want to be as close to other horses as they seem in the video, unsettled as well.
Now if you had a HUGE expanse and they were on the other side, then the likely hood that they would come all the way over just to get in your way is small but I wouldn't risk it in a smaller paddock.