As a matter of fact, the Raiden guy just contradicted himself (although he made his previous answer intentionally vague, so I guess that's his alibi). He said that there were only about 4 different creatures in the movie, then went on to describe them. Now, when someone brings up the snakes/cobraburster (which he had not previously mentioned in his creature-describing post), he says that "The snakes are some creatures among others and we don't see them so much time."
I find it hard to believe that this guy would have forgotten about the snakes in his earlier post. Actually, going through all of his responses, it seems like he's magically "forgotten" a questionable amount of information for a movie that he's seen what, 7 hours ago?
Of course, he could still be legit (and just have a horrible memory), but his strangely vague answers and forgetfulness is suspicious as hell.
EDIT: He also mentions different stages of "infections" when asked about the movie's creatures, then rescinds and goes on to speak vaguely of the different creatures. This guy smells fishy.