Fairfax County Board of Supervisors Chairman Sharon Bulova declared in her State of the County address Wednesday that Fairfax’s prosperity lies in the kind of grand, ambitious — and yet unproven — redevelopment that is underway in Tysons Corner.

Rather than delivering a traditional speech, Bulova (D) recorded her remarks in a YouTube video that takes residents on a tour of areas that the county is working to rebuild. Released Wednesday, the videotaped address was shot partly while Bulova was seated behind a desk and partly while she was standing in the wind in Tysons, a nearly finished stretch of the Silver Line soaring behind her.

After Tysons, Bulova takes viewers to Merrifield and Springfield — two other places where walkable, mixed-use centers are under construction.

Much of the 18-minute video resembles a marketing ad for the county — a wide-reaching and rosy look at what has been accomplished in recent years and what is on the horizon for Virginia’s largest jurisdiction, home to more than 1.1 million people.

But it is also a window into what Bulova and other top county leaders see as their best chance for solving some of Fairfax’s biggest challenges, including accommodating growth, meeting infrastructure needs in an era of increasingly tight budgets and easing traffic congestion that is among the worst in the nation.

The answer to all of those things, Bulova’s speech suggests, is the kind of redevelopment that is underway in the stops on the tour and that is vastly different from Fairfax’s suburban past: walkable, urban town centers near public transportation that include shopping, residences and office space. The county is pursuing projects that encourage people to live near their jobs and abandon their cars, and that rely more heavily on developers to build fire stations, parks, school, roads and similar projects in exchange for higher, profitable density levels.

“Fairfax County’s future is in redevelopment,” Bulova says in the video. “As Fairfax continues to mature, it’s important that we accommodate our future growth and existing population in ways that make it easier for our residents and workers to live, work and play without always needing to get behind the wheel of a car.”

The county’s effort to remake Tysons Corner is the most striking example of the kind of redevelopment that Bulova endorses in the video, if for no other reason than its scale. In short, the county is attempting to knock down and rebuild much of the 1,700-acre minicity, and what is there today — a sprawling, traffic-clogged office park — is the antithesis of what officials envision.

The county’s plan to achieve that vision is so ambitious that some question whether it is achievable. Observers say the biggest unknown is whether the market will support the millions of square feet of new office, retail and residential space that are in the works.

At least one supervisor, Pat Herrity (R-Springfield), has questioned whether Tysons’ product will ultimately be too expensive. In his own State of the County event Tuesday night, he called it “backwards progress” to ask developers to pay for affordable housing and other amenities — costs that will be passed down to tenants.

Speaking to reporters after a screening of her speech, Bulova acknowledged fears that businesses may not be immediately interested, especially in light of the threat of massive federal budget cuts.

“That’s an absolute concern that Fairfax County has,” she said.

But it is also a risk the county is willing to take, and in the video, Bulova points to signs of steady progress in Tysons: The first phase of the Silver Line, which includes four new stops in Tysons, is nearly complete. The 17 redevelopment proposals that are in the pipeline are in keeping with the county’s vision. New bus routes are coming online, and the county recently approved a plan to fund the transportation improvements that will be needed as Tysons transforms in the next 40 years.

In Merrifield, Bulova says in the video, a new 31-acre development known as the Mosaic District is “taking off” after being stalled by the recession. A new two-story Target, a Hyatt hotel and the Angelika Film Center opened in the fall. Eventually, the site will include 500,000 square feet of commercial space and 1,000 residential units. In Springfield, the Springfield Mall is being redeveloped into a walkable town center. Much of the old mall was torn down in the summer. Plans call for plazas, shops, restaurants, housing and a dog park.

The icing on the cake, Bulova told reporters, would be winning the regional competition for the FBI’s new headquarters. The bureau is looking to leave the J. Edgar Hoover Building in the District, and Fairfax County has proposed a site across the street from the old mall.