Look at the doorway and try to figure out what is inside. It should only take less than 1 minute. You might need to get as close to the screen as you can to see it.
Don't give up.
It scared the crap out of me. I tried it on my wife and she just said, "Oh, what's that?" When I told he she was supposed to be scared by it, she said, "Oh, no! That's how I feel like I've been around the house all day." (We have 3 kids, 8 and 5 (twins)).
Made me jump. Here I am looking at the doorway waiting for my eyes to cross and some weird shape to take focus and this thing....I won't say anymore. Pretty wild.