I don't know how you are lighting this, but generally speaking photographing flat work requires an even light source. Usually two diffused lights above the surface at 45 degree angles should accomplish this task. Your lighting suggests that you are not using a diffused source(s) as witnessed by the hot spot in the middle of your screen hence the halo effect.
Another thing I noticed is that you are using a camera with auto-exposure mode engaged, subsequently every time you move your hand into the frame the light value shifts. If this is a Point & Shoot camera then there is not much you can do about this, but if it's a DSLR you need to lock down the exposure so it is not changing.
There are three manual controls that generally should be locked down before recording:
1) white balance,
Many Point & Shoot cameras will allow you to set the white balance and focus, but not exposure.
If you are in this situation, then the only way to defeat the exposure changes would be to keep the light even through out the frame and sequence. For instance if you were wearing white gloves this would help keep the auto exposure from going lighter to capture your skin tone, or if you changed the back ground, and made it the same value as your hands--awkward yes, but even light would likely improve the entire scene.
Hope this helps