[seestheday]

It may be easier to think about this in meatspace.

Is it a crime for someone walking around to not look at a billboard? Of course not.

Is it a crime for someone to plaster over an ad on a billboard with their own ad? It isn't explicitly theft, but it is certainly a crime, and the end result is nearly the same (in the meatspace example it is the advertiser that gets the shaft, and in the digital example it is the billboard maker that gets the shaft).

[userbinator]

I agree with these statements, but the analogy is flawed because in your second example you are making it impossible for everyone to see the original ad. The software equivalent to your analogy would be hacking into others' servers to replace ads, making that replacement visible to everyone, and that is certainly not what Privdog is doing. This also happens to be the crucial difference between theft and piracy.

Privdog only replaces ads on the machine on which it is installed, and those who don't have it installed will see the original ad. The meatspace equivalent would be something like an augmented reality device that replaces ads for the one wearing it; and this is not a new idea, although no one has wanted to replace ads with other ads:

http://theartvertiser.com/