Already there are signs that these less formal and more individual efforts are filling a vacuum created by a decline in activity among the independent advocacy groups  so-called 527s and similar operations  that have played a large role in negative politics in the last several election cycles. Especially on the conservative side, independent groups have reported trouble raising money, and some of the biggest players from 2004 have signaled that they will sit it out this time around.

The shift has by no means gone unnoticed by the campaigns. And while strategists in both parties suspect that traditional political operatives affiliated with the campaigns or parties frequently pose as independent grassroots participants by hiding behind anonymous Web identities, few have been caught this year.

The change has added to the frenetic pace of the campaign this year. “It’s politics at the speed of Internet,” said Dan Carol, a strategist for Mr. Obama who was one of the young bulls on Bill Clinton’s vaunted rapid response team in 1992. “There’s just a lot of people who at a very low cost can do this stuff and don’t need a memo from HQ.”

That would seem to apply to people like Robert Anderson, a professor at Elon University in North Carolina whose modest YouTube site features videos flattering to Mr. Obama and unflattering to Mr. McCain, or Paul Villarreal, who from his apartment in Wilkes-Barre, Pa., has produced a harsh series of spots that attack Mr. Obama and make some claims that have been widely debunked.

Counting the audience for such videos can be tricky, as sites like YouTube list only the number of times they have been viewed, not the number of people who view them. That said, according to YouTube, Mr. Villarreal’s video was viewed about 50,000 times. And it cost him just $100 to produce, for software, he said. He said he had no connection to the Republican Party or the McCain campaign, though he said he had reached out to them and not heard back.

The better-circulated political videos have generally come from people with some production experience. One of the most widely seen anti-Obama videos was created by Jason Mitchell, who produces evangelical Christian programming in Durham, N.C.