a kitty that won't mind you making weird noises or waving things in the air, but will be interested
a working video camera
string or yarn
Step 1: A noisy method.
A problem with this method is you may not want these noises in your final video, so you have to over lap with music or another audio recording of the room without the noises.
Step 2: A drunken method.
Wave the cat nip (or cat nip filled toy) under your cat's nose. Now, turn your camera on, and start recording.
Move the catnip above the camera the way you want your cat to move it's head. Be aware that the catnip may be replaced with something that your kitty likes. (Example, if your kitty is Garfield wave lasagna over or under your camera.)
This method may take a few tries.
Step 3: Dangling by a thread.
Take your thread and dangle it above your camera. This could be used to make it seem like the cat is trying to reach something.
Well, there you go. I hope to have a video with these 3 things soon.