The player: Schuyler Cullen, co-founder and CEO of Keystream, an online video ad-serving company.

The play: Keystream’s technology lets Web publishers insert interactive overlay-style ads into their online video content. The company works directly with publishers to integrate its tools into their online video programming. Keystream does not deliver pre-roll ads.

The pitch: Keystream analyzes the video to find the most appropriate location visually in which to place an ad. For instance, in a soccer video, Keystream might insert an overlay ad when the video shows the grass on a soccer field and then turn the ad off when the video pans to the players. “We identify automatically the location where we can insert the advertiser,” said Mr. Cullen.

In the mix: British broadcaster ITV is the first Keystream client. Keystream competes with other ad insertion technologies such as Kiptronic, Castfire and Freewheel and also goes up against ad networks such as Broadband Enterprises and Tremor Media. But Mr. Cullen is positioning Keystream as a complement to ad networks because it can deliver a new ad format for ad networks to sell. Keystream does not sell ads itself. ITV has generated a 5% click-through rate in the first few months of using the service. Mr. Cullen said he is in talks with media companies in the United States.

The backstory: Founded in 2004, Keystream operated out of Mr. Cullen’s garage until 2007. He raised $500,000 from angel investors and landed $800,000 in venture funding from Voyager Capital this year. Keystream makes money based on a fee for the ads it delivers for publishers. Based on initial projections, Mr. Cullen expects the company to be profitable at the end of next year.

The pros: In a tough economic climate, advertisers crave more accountable and targeted ad formats.

The cons: As a new player, Keystream must grow awareness quickly in a hyper-competitive business.

Background: Mr. Cullen was born and raised in Chico, Calif. He earned a bachelor’s degree in physics and mathematics from Caltech and a Ph.D. in theoretical physics from Stanford. Before launching Keystream, he worked as a scientist at Pulsent Corp.; his papers have been cited more than 400 times in scientific publications, he said. He lives in Mountain View, Calif., with his wife.

Who knew? Mr. Cullen is an avid rock climber.