Snapchat's foray into premium video advertising, with the exclusive marketplace to link brands and top-tier publishers it launched last year, is winning over advertisers with the amount of control it gives them to choose where ads run. Early media partners, however, say they're disappointed.

It's been a little more than six months since the private marketplace opened, and some publishers have yet to see the financial benefits, according to one top publishing partner executive, who spoke on condition of anonymity.

"We make some money there, but it was posed to me, at a time of year when we needed to drive revenue, that this was awesome, a way to totally crush it," the exec says. "Then we went live, and money was just barely dripping in. Like when it's misty outside, and not quite raining, it's annoying."

Meanwhile, advertisers say the pricing is higher, but the guarantee of running video ads, which can't be skipped, with assurances of brand safety, makes it an attractive way to buy.

The new method of selling ads has failed to impress some publishers, who were already fumbling for the right formula on the app that has constantly had to reinvent its media proposition. Snapchat has split ad revenue with media partners since it launched the Discover section in 2015, with Hearst, ESPN, Vice, CNN, People and others.

The past year has been a difficult one, however, with publishing partners like Hearst--on Discover since the start with Cosmopolitan--rethinking their strategies and closing underperforming channels. Condé Nast also paired down its publishing footprint there. Meanwhile, organizations like the National Football League and National Basketball Association grew, but they are less concerned about ad revenue than traditional publishers.

Snapchat's private marketplace, which mirrors similar ad offerings from Facebook and Google, was designed to connect discerning brands with only the most qualified publishers. Instead of buying ad space in an open auction with no certainty over where an ad will run, brands could enter the private market, where they could control what media they wanted to support. It was also meant to give publishers the ability to choose the advertisers and potentially raise the amount of money they make from ads, because the inventory is valued higher in the private auction.

Publishers, however, don't have the power over ad deals that they hoped. They don't have a direct relationship with advertisers, and all they can do is select 100 brands to pre-approve to buy their ad inventory. "A traditional private marketplace is when a buyer and seller talk," the publishing exec says. "They create a unique connection."

Snapchat has limitations for publishers compared to larger rivals like YouTube, Facebook and Facebook-owned Instagram. For one, its audience size is 186 million a day, while Instagram has 500 million and Facebook 1.5 billion. YouTube says it has more than one billion viewers. Publishers can't promise advertisers the same potential to hit outsized campaign goals on Snapchat.

"Given the daily usage on Snapchat and the footprint of the app, you just realize how much smaller it is that Facebook or Instagram," says one ad agency exec, who spoke on condition of anonymity. "It's just a tougher sell for brands."

A Snapchat spokesman says that the private marketplace is in a limited testing phase and will evolve. Even the name will change to "premium content targeting." The next phase of the platform will allow for more customization on the part of ad buyers, letting them bundle specific shows and channels from different media partners, and then compete in an auction for the inventory on a more refined set of content. For instance, an advertiser could mix and match individual shows from Hearst and Condé Nast without running ads on all the shows from those publishers, some of which may not be the right contextual fit.

The Snapchat spokesman says that Discover as a whole is growing, with 30 percent more people frequenting the media partners and watching original shows there compared to last year.

"We're proud to have added transparent Premium Content Targeting with publisher-centric controls less than 18 months after launching self-serve [advertising]. We believe the pace at which we moved shows our ongoing commitment to our publishers," the spokesman says in an e-mail statement. "In addition to our deep investment in Shows and introduction of six-second full-view commercials, we expect to bring this Premium Content Targeting program out of beta in 2019 with significant improvements to provide yield and flexibility for publishers, and ROI and transparency for brands."

The flexibility is great for advertisers. They are able to target the ads using the same sophisticated techniques, refining the audiences they want to reach, while only running with the best media. The private marketplace also lets the advertisers choose to buy only six-second ads that viewers can't skip, which are typically preferred over the ones that viewers can just tap to dismiss.

Prices are nerly five times higher, advertisers say. A six-second ad can cost $10 for every thousand views, while the average Snapchat ad costs closer to $3 for every thousand views.

"We've seen pretty good demand because of the premium content and efficient rates," says Aaron Goldman, chief marketing officer at 4C, the marketing technology platform. As "far as performance, most advertisers are looking at cost per completed view so the metrics are good thanks to non-skippable format."