That's Tim Man in the monkey mask, and Tony Jaa is praying before he kicks Tim in the head. Man was in last year's Fighting Beat (if I remember correctly, he played one of the leading bad guys) and also filmed Bangkok Adrenaline.
Jaa is directing Ong-Bak 2 himself. It is filming now and is due out sometime later this year.
A plot synopsis for Ong-Bak 2 was offered up at the Cannes Film Festival last year. Here it is from TonyJaa.Blog.FR:
Set in the regal times of King Naresuan, Tony Jaa plays Tien, a man who was born into nobility but had it stripped from him after his parents were brutally murdered. During his childhood Tien learned Khon, a form of dance which is usually reserved for royalty.
Although he didn't know it yet Khon would later prove to be an invaluable aide to him. After seeing his parents murdered at the tender age of 10, Tien is forced to live on the streets where he is eventually captured by a group of thieves who take him in and teach him how to steal and fight. Tien expertise as a thief and fighter grows and it isn't long before he is made head thief.
Then Tien sees something that makes his stomach churn. A competition is being held to find the best knights to serve under the very man who had killed Tien's parents all those years ago. Tien passes the tests easily and is made Lord Rachasana's second Knight.
Now, he has his opportunity to strike but he will have to use all his skill and ingenuity if he is going to get his revenge on the man who killed his parents."
Meanwhile, Tony Jaa has also been cast in a small role in M.C. Chatrichalerm Yukol's Naresuan III, which judging from the period haircuts of cast members at the recent awards ceremonies, must be filming right now, too. The third part in the Naresuan trilogy was to have been released for His Majesty the King's 80th birthday last December 5, but maybe now it will be ready for HM the King's 81st?