The attack, which is under investigation by Kerry Gardaí, is believed to have occurred off Chapel Place, in Killarney town centre, last Saturday evening.
Up to six youths and young men were caught on the footage attacking the prone youth who was lying on the ground and desperately trying to shield his head and face.
While lying on the pavement, attempting to curl into a protective ball, the youth is kicked and punched by the group of at least six youths.
Gardaí became aware of the matter when footage of the incident was circulated locally on social media.
Various different clips of the attack have been posted online - though the faces of none of the attackers are visible.
It is believed the footage was taken primarily by one smartphone.
Gardaí believe the attack occurred at Chapel Place near New Street sometime between 4pm and 9pm on Saturday.
Officers are now working to verify the footage and trace who shot the clips.
Gardaí were called to an incident in Killarney town centre on Saturday evening and are working to determine if this may be somehow linked to the video footage.
It is understood gardaí are now checking CCTV security camera footage from various premises around Killarney town centre in a bid to determine the movements of groups of youths around the time of the attack.
Radio Kerry has reported Gardaí are also making local inquiries to verify the footage and whether the incident involved was witnessed by local residents.
Killarney town centre was extremely busy last weekend and officers believe that, if the footage is genuine, a large number of people must have witnessed the incident or its aftermath.
A garda source indicated no arrests have been made and officers are still working to analyse the footage.
There have been no reports as yet of anyone suffering serious or critical injuries as a result of an assault at the time involved.