Roku shares fell 22 percent Thursday, their worst drop since the company had its IPO in September 2017, even though the company beat third-quarter earnings estimates on the top and bottom lines. One key metric that fell below expectations was platform revenue, which encompasses streaming advertising.

Platform advertising is shaping up to be an increasingly important component of the company's strategy because Roku is in talks with media companies it hopes will bring more content to its app, CNBC reported Wednesday. While Roku reported total revenue of $173.4 million compared with the $169.1 million analysts surveyed by Refinitiv were expecting, platform revenue was $100.1 million for the quarter versus the $103.2 million forecast by StreetAccount and FactSet.

Roku has not been able to make as much money per customer as analysts expected, reporting average revenue per user (ARPU) of $17.34, below the $17.44 forecast by StreetAccount.

In an interview on CNBC's "Squawk Alley" on Thursday, CEO Anthony Wood touted the effectiveness of the company's platform for advertisers trying to reach viewers in the 18-to-34-year-old demographic.

"If you're an advertiser, you're seeing your viewers shift from traditional linear TV to streaming," Wood said. "Ten percent of the people in that key demographic have shifted not just to streaming but to Roku in particular, so if you want to reach them with a video ad, you need to advertise on Roku."

He also said streaming ads "are just a fundamentally better advertising unit" than traditional TV ads because advertisers know what they are getting out of their spending. When Roku shows advertisers data on how their ads perform, Wood said, "that helps advertisers have the confidence to increase their budgets."

He acknowledged the ad dollars could take a while to catch up to the technology.

"When viewers moved to mobile, the ad dollars took a few years to catch up. But they will catch up," Wood said.

Analyst notes Thursday morning still indicated confidence in the stock, ranging from neutral to buy ratings. Guggenheim Securities wrote that Roku's "stated initiatives and potential expansion opportunities are under-appreciated," citing its established technology and user base as advantages in the competitive streaming space.

D.A. Davidson gave Roku a neutral rating, on the other hand, as the increase in active accounts missed its estimates but still "was more than offset" by increased streaming hours and ARPU that beat its expectations.

—CNBC's Sara Salinas contributed to this report.