This is the first week that Romney outspent Obama on ads. Add in the super PACs and Romney has about a 3:2 advertising advantage this week. Obama spent more in absolute terms and versus Romney last week, including on a two-minute ad that ran before the first debate.
Perhaps, Romney spend his ad money on programs frequently viewed by Republicans, while Obama has targeted programs more to the liking of Democrats? I read a fascinating article once about how Republicans, among others, tended to prefer shows about work such as "The Deadliest Catch," while Democrats, among others, preferred shows with moral ambiguous heroes such as Dexter.
Obama has made national ad buys on networks like MTV (to reach younger voters), on late-night TV talk shows, and during the baseball playoffs. Romney hasn't made many national media buys and is targeting the swing states directly. Obama's media campaign, which employs a team of outside media buyers, is supposedly more targeted than Romney's, where one or two people in-house are deciding on which media to buy. Obama is reportedly more up on local swing state cable than Romney, too.
Yeah, I was watching some movie on Lifetime with my family and I saw an Obama ad attacking Romney.