Doug Mataconis thinks through political commercials in the Tivo era:
...there are some forms of television programming that typically aren’t watched on a delayed basis, specifically news and sports. As DVR use increases, you’re likely to see political advertising concentrated around these types of programs where the audience is more captive than it is for, say, Wednesday night’s Law & Order: Special Victims Unit.
I’ve been watching the baseball playoffs all month, for example, and even though the part of Virginia I reside in doesn’t have any competitive races, I’m still seeing ads for candidates in surrounding Congressional Districts. Campaign ads are also showing up during the local and national news on the broadcast networks, and on the cable news networks. As long as that audience is still there, campaigns will continue buying ads.
Second, the types of programs that most people record on their DVRs, evening comedy and dramas, aren’t usually the ones where you see much political advertising to begin with. Partly this is because the commercial time for these shows belongs, mostly, to the networks rather than the local stations and it makes little sense for a Senate candidate in Nevada to buy national television time. Obviously, this will be different in a Presidential campaign year.