First Guess: You have air in the ABS unit that cannot be bled out without the scan-tool procedure.
The accumulators in the ABS module trap air. Bleeding at the wheels does not remove air trapped in the accumulator(s). The ONLY way to get this air out is to force the ABS unit to activate. ("Chattering" the ABS) That can get the air out of the ABS unit, but it still has to be bled down the tube/hoses and out the wheel cylinders/calipers.
The video previously posted is not bleeding the ABS unit; it's bleeding the combination valve. The combo valve is bolted to the ABS module, but isn't really a part of the ABS module.
It just kills me that the guy in the video is pouring clean, fresh brake fluid into a reservoir filled with black, dirty, contaminated fluid; even the plastic of the reservoir is black with crud. For ****'s sake, suck the dirty fluid out of the reservoir leaving only enough to prevent air getting into the master cylinder; wipe the crap off the plastic of the reservoir, and THEN pour clean fluid back in to the appropriate level.