There is no backinfo to go with this video, except that the three men shown being abused and beaten were alleged robbers.
The video shows the alleged thieves after they were stripped naked (or half naked, but always with pants down exposing the nether region). One of them is being delivered beating with a plank of wood on his bare ass. The other two either already got theirs, or were about to, but I presume the former.
The incident most likely happened in Africa, but I don’t know where exactly. The abuse seems to be delivered by military people.
Props to Best Gore member @african-angel for the video: