He continues. Note the position of his hand -- forefinger extended, middle fingers curled, but knuckles up.
And here's more evidence for the "it's a fake" file. The video originally led you to the turtlekid site -- now defunct -- which was full of home-made-looking TMNT-related videos, designed to promote and sell TMNT toys and movies and such. Note the 2006 copyright by Playmates. If this were a real video of Zach, made by his dad -- why would the TMNT toy company own it? And if 3 year old Zach was painting like this in 2006, why have we not heard anything of him since? Where is 10 year old Zach, and why haven't we seen a whole slew of astounding paintings by this kid?