The news: X launched React with Video, a feature that lets users post video responses using green screen, split screen, or picture-in-picture—without relying on third-party editing tools, per TechCrunch. The tool is live on iOS, with Android and web versions planned.

React with Video targets creators who build personal brands through commentary on news and politics. The feature marks X’s deeper push into the vertical video format that TikTok popularized and YouTube, Instagram, Facebook, and even streaming services have since copied.

Why this matters: X’s global user count is rising, but its US user outlook is less rosy.

• It reported 550 million users worldwide in March 2026, up from 520 million in December 2025, per Social Media Today, but we expect X’s US user base will drop from 51.7 million this year to 48.2 million in 2030.
• We forecast the gap between X’s audience and TikTok’s will widen over the rest of the decade: X will slide from 21.4% of US social network users this year to 19.0% by 2030 as TikTok climbs from 54.9% to 64.0% of US social network users over the same period.

Vertical video is worth the fight because of the time it commands. US teens who use TikTok spend 1 hour and 31 minutes per day with the app in 2026, per our forecast. React with Video gives X a native way to compete for that attention without pushing users to a separate editing tool like ByteDance’s CapCut.

In addition, short-form video is the brand content type that X users are most likely to interact with, at 37%, just ahead of text posts at 36%, per Sprout Social.

Implications for marketers: Reaction videos let creators fold brands into a proven format through live commentary on news, culture, and viral moments—an ideal surface for marketers to court creators for on-brand reactions. However, X’s weak ad business and brand-safety record temper the opportunity.

Since any user can overlay commentary on brand posts, marketers should monitor mentions and reaction videos closely. With the feature limited to iOS at launch and X’s US user share still sliding, marketers should treat the feature as a test and watch for the Android rollout and creator uptake before committing core spend.