Supply-side video ad platform SpotXchange released new data this morning highlighting huge growth in mobile video advertising and private marketplaces by premium publishers.

SpotXchange said it experienced 800% growth in mobile video ad spending in the first half of 2015 vs. the first half of 2014 as mobile accounted for 19% of total spending on its platform vs. just 4% a year ago. There’s almost certainly more rapid growth ahead, as recent data from Ooyala revealed that 42% of all video views in Q1 were on mobile, with 50% expected later this year. eMarketer is forecasting mobile video will account for $2.62 billion or 34% of the $7.8 billion expected to be spent on online video ads this year.

Advertisers are shifting their spending to align with these new viewership patterns. SpotXchange’s CEO Mike Shehan also noted that advertisers are now using mobile video for brand-building, in addition to traditional direct response performance-based and cost-per-acquisition efforts. As a result, Mike expects mobile video CPMs to increase as 2015 unfolds. All of this is part of the huge changes mobile is bringing to the video world.

SpotXchange also said that inventory in private marketplaces, in which premium publishers sell video ads programmatically to a selected group of advertisers, has grown to become 40% of the video impressions on its platform in 1H ’15. That’s an increase of 112% vs. 1H ’14. SpotXchange is enabling publishers to evaluate performance across private marketplaces, public marketplaces and direct sold for improved yield optimization.

Fueled by a $144 million investment that European broadcast giant RTL made for a 65% stake in SpotXchange in July, 2014, the company also opened 3 new offices, in Amsterdam, Hamburg and Singapore and increased its headcount by 54, a 28% jump. The company also added 140 new customers including E.W. Scripps, Meredith Local, TV Insider and others.