At the age of 21, David Pakman started a little Massachusetts community radio talk program. While the young broadcaster got his show syndicated on a few public radio stations, it was a YouTube channel he began in 2009, “The David Pakman Show,” that opened up his progressive political commentary to a whole new digital audience. The show has since amassed 353,000 subscribers, and roughly half of its revenue now comes from the ads that play before his videos. He earns enough to produce the show full time and pay a lean staff.

Or, at least, he used to. Last month YouTube announced abrupt, vague changes to its automated processes for placing ads across the platform. Ads on Mr. Pakman’s YouTube channel evaporated, dropping to as little as 6 cents a day, and forcing him to set up a crowdfunding page to help cover $20,000 a month in operating costs.

“This is an existential threat to the show,” Mr. Pakman said. “We need that money.”

Since its 2005 debut with the slogan “Broadcast Yourself,” YouTube has positioned itself as a place where any people with camera phones can make a career of their creativity and thrive free of the grip of corporate media gatekeepers. But in order to share in the advertising wealth a user base of more than a billion can provide, independent producers like Mr. Pakman must satisfy the demands of YouTube’s unfeeling, opaque and shifting algorithms.