Yahoo is looking to turn around its falling ad revenue with its latest purchase of video advertising company BrightRoll Inc. for $640 million. It’s the company’s second largest deal, just over half of the $1.1 billion it paid for its Tumblr acquisition last year. But unlike the Tumblr deal, which has yet to prove profitable, BrightRoll may provide an immediate return to the company, with revenue expected to exceed $100 million this year, according to Yahoo.

“BrightRoll is the next piece of the puzzle that will allow Yahoo to monetize online video content outside the confines of its owned and operated websites and apps,” Nomura Securities senior analyst Anthony DiClemente wrote in a research note.

It’s a deal advertisers have been clamoring for two years, since AOL spent $405 million to acquire Adap.TV, a competing video advertising platform. But AOL has been laying the groundwork for its video ad business since 2010 when it bought video ad network 5min. It took Yahoo four years to respond, but its stock price is up nearly 3 percent since the deal was closed and several investment firms are raising their price targets in response to the acquisition.

Despite all of this, some investors are still unhappy with the turnaround moves made by Yahoo CEO Marissa Mayer and are looking for quicker returns. At least two of the critics are some of Yahoo’s top shareholders, who have directly pleaded to AOL CEO Tim Armstrong to consider a merger between the two companies, Reuters reported on Wednesday. Their move follows a push for an AOL-Yahoo merger from hedge fund Starboard Value LP, in an effort to free up Yahoo’s stakes in Asian Web companies.

It’s an odd move for the hedge fund firm, considering that it had previously criticized AOL in 2011 and 2012 for poor investment returns from its acquisition of the Huffington Post and Patch. But now, Starboard CEO Jeffery C. Smith sees a merger as the best way for Yahoo to give its shareholders a return on their investment. Were such a merger to happen, Starboard would want Yahoo to merge its Web and email business into AOL to free up its holdings in Alibaba and Yahoo Japan into a separate company.

Yahoo made $6.3 billion from Alibaba’s IPO and promised to return half of that to shareholders in the form of stock buybacks.

Whether a merger is considered, the Yahoo Brightroll deal is expected to be a positive for the company as it looks to augment its display advertising business model with digital video ads, an advertising industry segment that's expected to grow 42 percent to $5.96 billion this year, according to eMarketer.

Despite potential gains from video advertising for Yahoo, analysts note that the company has a number of hurdles to clear before it can seriously compete in digital video advertising market, including competition from Google’s YouTube, which accounted for 18.9 percent of the U.S. digital video ad market. There’s also the question of whether  the company plans to buy more ad tech, according to a research note from Pivotal Research group senior research analyst, Brian Wieser.