Why do Buddhism monk hits people in the head? i saw this video on facebook and youtube ,

https://www.youtube.com/watch?v=CHDp1GbzE4o

and they're writing on it in arabic 
"الرقية الشرعية عند البوذيين "
witch means "the buddhism's Exorcism" 
i want to know if this is really a buddhism exorcism . if not , what is it ?
I don't think it's a usual practice. I found this explanation online:

A monk who was seen forcefully hitting temple-goers' heads with a bundle of dried grass has defended the unorthodox practice, calling it his unique way of blessing the faithful.
Phra Jirapan Analyo, the 53-year-old abbot of Pha Sadej monastery in Saraburi, admitted that the practice may look violent in a video that went viral this week, but insisted that it does not hurt.
&quot;The knocking of heads is a way to cure diseases and illness for the faithful,&quot; Phra Jirapan said. &quot;And the knocking may look violent, but it didn't hurt anyone.&quot;
...
Phra Benja Papassaro, a monk who oversees temples in Saraburi province, told reporters that he watched the video and believes &quot;his action does not violate the holy doctrines, though it does look excessive.&quot; He said he and other senior monks are discussing the issue to find a formal conclusion on the matter.

A more usual form of Thai &quot;blessing&quot; would be &quot;sprinkling&quot; water (see for example here).