Ranpo jigoku

I thought the movie was... interesting. Some parts a little too artsy. I'm not really here to debate the movie but, to ask about the warning in the beginning. What are the EXACTLY talking about pertaining the "intended effects"? I'm not sure if they're talking about the blockey distorted appearance of a scratched DVD or if its just the one I'm watching. After a few minutes it gave me a little headache. I thought that that was what they were warning about until towards the end when the guy in crawling bugs says, "what was I thinking?" then the movie was "normal". I had rented the movie from Blockbuster and it was brand new and undamaged.