I tried to verify. Actually there is a lot of addresses which could be used. The first one is qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqr5w5w5x8rwhc with the payload 0x7475. This is strange.
I followed their process: start "with the 160-bit all-zero hash value" and loop "upward with step-size 1 until an address ended with substring 'whc'".
I just looked at it, I used a python script of my own. Even if I search for "[0-9]8whc" (which is described in their code), the first address I get is not the right one.
