Gardaí are investigating an alleged serious assault on St Patrick's Day in Dublin.
The incident took place on Aston Quay in the city centre on Monday afternoon.
A video, which shows a man lying on the street being attacked by a group of youths, was posted on YouTube.
It shows one of the attackers kicking the man in the head, apparently knocking him unconscious.
The video was later removed from YouTube.
Two youths have been identified from the footage, which was filmed by a passer-by, but gardaí are still trying to identify the victim.
Gardaí have appealed to anyone who knows who he is to contact Pearse Street Garda Station.