The main Nayanthara MMS scandal involves oral sex. The man involved in this video is rumored to be Simbu (an ex boyfriend). Nayanthara has always been consistent in her denial that this video does not involve her. Nayanthara says that the face, which is undeniably hers was morphed on using sophisticated computer graphics.
Another rumor behind this MMS video is that the man involved in the video was Shaji. The rumor is that Nayanthara had to give oral sex to get her role in the film Vallavan (her 13th film), which Shaji directed. People say this video was shot at a time when Nayanthara was new to film and this was a "casting couch" type of experience.
Shaji has always refuted these rumors. Many say though that the reason for Nayanthara splitting from Simbu at this time was because of the "casting couch".