Ah, green screen technology. It opens up so many possibilities to the broadcaster looking to transcend both space and time. It can make our show's set stay the same, even when shooting in New York or Atlanta, so that you have to take Joel's word that he's actually where he says he is. It can also scare the living bejeezus out of Global BC's weather woman, Kristi Gordon. Basically, what we're saying is that it's the Philosopher's Stone of television magic.
It may seem like an over-reaction on her part but primal instinct is a hell of a thing. Kristi knows there's not really a 5-foot tall spider, poised to sink it's fangs into her from above but when a person sees that sort of image in the monitor, it's hard to override one's fight-or-flight instincts. Plus, Kristi doesn't really get along with bugs. They have a history together and it hasn't been an entirely pleasant one.
So you see, it's not just a case of arachnophobia. There's a persecution complex in play as well. If arthropods really do have it in for her, though, we're not about to intervene. They reliably produce great television together and we're not going to get in the way of what's obviously some very powerful on-screen chemistry.