Video ads are the wave of the future — at least that's how it looks for a lot of companies. According to eMarketer, digital video advertising will grow by 42% this year for a total of $6 billion in revenue allocated. With different acquisitions and technological innovations, these four companies are helping to push the video ad space forward.

1. Facebook 

This spring, Facebook rolled out auto-play video ads on users' news feeds. The move has been controversial among users and some marketers, but brands like NBC, Progressive, and the Macy’s have jumped on board with the ads. 

More recently, the social giant acquired ad-tech firm LiveRail in an effort to expand its video advertising business. The third-largest video ad seller, LiveRail automates the video ad buying process. Publishers need only upload their inventory and LiveRail solicits buyers through an automated auction. Facebook wants to use the technology to offer more options for advertisers on its platform, including better targeting. It plans to keep LiveRail’s business of selling ads off of Facebook operational at the moment, and while no plans have been confirmed, it’s a safe bet the social network will eventually sell its own inventory with LiveRail, too. 

2. Fuisz Media 

Fuisz Media, a tech firm in Santa Monica, CA, just raised $2.1 million in funding to develop a technology that allows advertisers to integrate interactive elements into their online video advertisements. Needless to say, some major brands are excited. 

For example, Kraft — the first brand to test out the technology — can run certain spots for its brand Cool Whip that allow for viewer interaction. Waving the cursor over the ad can trigger a pop-up with a pastry recipe or additional information about the product. Brands are hoping the interactive elements will give viewers pause and offer more value for them to finish the ad. At the very least, they should grab more attention than a traditional pre-roll video ad. 

3. BrightRoll 

In 2006, privately owned video ad exchange BrightRoll made history when it bumped search giant Google from the number one spot for the largest video ad reach in the U.S. Since then, it has been in and out of the top spot, but is always a fierce contender. Currently, the video ad platform delivers streaming video ads to 51.3% of the population across the web. 

Not only has BrightRoll been able to establish a formidable presence, it has been involved in projects that are changing the digital video ad landscape as we know it. It partnered with Nielsen to release Online Campaign Ratings for digital video ads and served an integral part of bringing the ratings to mobile. MediaMath also tapped the firm to help build out its video ad exchange offerings earlier this year. 

4. Google

In its continuing quest to be the best at everything, Google has made a few strides toward video ad offerings, as well. Just last month, it acquired digital video ad-tech firm mDialog to expand the ways its brand customers can purchase video ads. 

With the mDialog technology, Google customers like NBC and Fox can run digital video ads against their shows. The multiscreen offering is something a lot of advertisers and publishers have been working toward, and mDialog’s technology is also slowly being integrated into Google’s DoubleClick suite — a move that will result in a wider range of options for digital video ads.