After Wall Street analysts peppered Facebook CEO Mark Zuckerberg on Wednesday about the social network’s Messenger and WhatsApp businesses, he told them they were missing the point. The biggest question on Facebook executives’ minds these days, he said, is whether it can pull off its ambitious video strategy, which includes rolling out TV-style programs as well as shorter videos on a new section of the app known as “video home.”

The key is making sure that videos are compelling enough that users spend “incremental” time in Facebook’s app watching video, in addition to their News Feed scrolling, Mr. Zuckerberg said on the call.