Rhythm NewMedia released some interesting findings today about mobile video viewing as it relates to its ad network, including that mobile video viewing continues to be spread throughout the day rather than spiking during primetime like it does with regular TV.

Rhythm’s network grew 30 percent in the second quarter – faster than industry forecasts for mobile video, says Rhythm CEO Ujjal Kohli, who notes that the mobile video ad industry is just getting started.

Rhythm also found that Android users seem to be on 3G a lot more than iPhone users – 72 percent of mobile video viewing via Android was done over 3G and 28 percent over Wi-Fi. Viewing on iPhones, on the other hand, was split more evenly, with 56 percent over 3G and 44 percent over Wi-Fi. “We don’t know for sure why,” Kohli says. But one can theorize that Android users on Verizon Wireless don’t experience as much network congestion as an iPhone user on the loaded AT&T network, so iPhone users are switching more often to Wi-Fi. But, he adds, “that’s just conjecture on my part.”

While Kohli and many others believed mobile video viewing would be dominated by “snacking,” or small snippets of viewing, Rhythm actually found viewing time for full episodes increased 20 percent quarter-over-quarter. After starting to view a full-length episode, which typically lasts 45 minutes, 26.5 percent watched the entire episode and 41 percent watched at least half of the episode.

According to Rhythm, the mobile video sector is exploding. “I have said and I maintain that search and banner ads on mobile were just the warm-up act,” Kohli says. “The real show is going to be rich mobile video ads,” which is the opposite of online, where search led as the biggest market for advertising.

While the increase might not be all that surprising given the plethora of smartphones hitting the market, it bears repeating that the figures are from the first half of this year. The fourth quarter traditionally is the heaviest time for advertising in general.

Rhythm has been around for about five years and originally started serving mobile operators but terminated the on-deck business entirely to focus on off-deck. The company concentrates on top tier publishers; it does not pursue the long tail of content at all, according to Kohli.

Publishers and advertisers working with Rhythm include BMW, Pepsi, MTV, Discovery Channel, HGTV, CBS News, ET, AMC, Cisco, American Family Insurance, Audi, Cadillac and MasterCard, to name a few on its website.

The company’s latest report reflects ads shown over 325 million average monthly views in the second quarter, on iPhone, iPod Touch, iPad and Android devices in the U.S. market. The data is based on ad campaigns from 14 of top 20 U.S. advertisers, including more than 75 Fortune 500 brands.