One of the things about giant monster movies is that the monsters tend to display radically varying intelligence. Sometimes, they display adaptability and tactics that are admirably clever. Other times, they pull stupid stunts that make it clear why there's only ever one of the darned things.
Stupid behavior: Displaying interest in humans. Why? Despite this clip, we're not exactly ideal prey animals.
Zedus there, from a Gamera film, ought to be looking for better prey. In a fairly literal sense, we're pretty buglike (not to mention bony and full of gristle) next to a monster that size, and we probably shouldn't draw much of its interest except when our tanks and planes start pounding on it. Imagine going around scraping up clusters of ants and shoveling them into your mouth. Does that sound appealing?
It gets sillier, of course, when a truly large monster like Godzilla displays that much interest, though in Godzilla's defense, he seems to be smart enough to draw some form of amusement from stomping things, and he's never wasted time or energy eating them. (That, of course, opens up the question of what he does eat; in a discarded scene from an '80s-era Godzilla film, he killed and ate a smaller monster, and the much-maligned creature of the American film explicitly ate fish, but there's not really an official explanation of how he nourishes himself.)
And here's a clip from a film wherein the monsters just plain stink at fighting (1999's Reptilian, a remake of a film called Yonggary about a monster named Yonggary). Terrible aim, clumsy attacks, and... What the heck is up with Cykor's (the bigger, uglier monster's) not being impeded by losing its head, but exploding when a fireball (which it could produce itself) went down its throat? (Okay, so that's got nothing to do with intelligence, per say, at least not that of the monster...)
I mean, I appreciate that this is an inventive fight (and it is), but it's also just bad (and it really is, as numerous YouTube commenters and a really, really large number of reviewers, critics, and monster fans will attest).
Also, has anyone else noticed that Asian studios are usually really bad at CGI?