The creator of this, Greg Slepak, is very active in all kinds of blockchain technologies. My guess is that if this saw significant use, or bugs were reported, he would jump back on it full steam.

I think Slepak said he's waiting on Ethereum or blockstack to pick up where namecoin died.

At best, one can prove that the ad was served to a computer, not actually viewed by a user. Unless there's an incentive for the user to view the ad, as there are rewards for mining blocks, this model probably wont work. Granted, there are ways to incentivizes the user, such as paying users to view ads, but this kind of defeats the purpose of getting the user to pay your and doesn't really require a blockchain.

How would this work? Ad-viewing is a client-side function.