An important stage in the development of Superman: Clark learns that magic exists and that he is vulnerable to it. There are at least two mysterious forces: magic and Kryptonian tech. The witches try to control the tech but, at the end of the episode, it works against them and for Clark.
Smallville characters regularly behave out of character when they are possessed or when they are influenced, e.g., by Kryptonite or magic. Clark was possessed by Lionel. Lana, Lois and Chloe were possessed by seventeenth century witches. The difference is that someone who was possessed cannot remember their bizarre behavior.