''Beginning'' stretches the truth: Star Tony Jaa's splashily violent fightfest follow-up to his 2003 breakthrough martial-arts saga, Ong-Bak: The Thai Warrior, qualifies as a prequel. Unlike the original, which was set in modern times, Ong Bak 2: The Beginning takes place in ancient Thailand. Other than that, don't look for continuity of story line — just enjoy the extravagant fight stunts, the restless camera work, and the sluicing rivers of blood and mud. (That's why you're here, right?) Jaa, mesmerizing as ever to behold with his pinwheel moves, also (co)directs for the first time.
