If you somehow get to this page to print some coupons, save your ink!
Reader Amanda B (Thanks!) has pointed out that the coupons print without the barcode (see below) that the cashiers scan. She called customer service and was told that they would not accept those coupons.
The coupon at the bottom is the one that printed from Wal Mart's site, with no scannable bar code. The one on top is what a normal printable coupon looks like, with the scannable barcode circled.
She even asked them to remove the coupons from the website if they are not going to take them, but they are still there.
So, you can try to print them and pick a fight, but this is just a heads up that they may not work for you.