Video shot at 16:9 aspect ratio — the standard for YouTube long-form, webinars, and traditional broadcast.
Horizontal video is the desktop and TV-native format: 16:9 aspect ratio, typically 1920×1080 (1080p) or 3840×2160 (4K). YouTube's long-form feed, Vimeo, webinar platforms, and TV all expect 16:9. Mobile YouTube also renders 16:9 cleanly in the embedded player.
Horizontal works for content viewers commit to: tutorials, interviews, essays, gameplay. It does not work well in vertical-first feeds (Reels, TikTok) where it shows up letterboxed and the algorithm downranks it.
The common production pattern: film once in 4K horizontal with the subject framed loose enough that a 9:16 crop from the center still works. One source produces a 16:9 YouTube upload and a 9:16 Reel/Short crop. Kompozy's clipped-shorts path does this crop automatically with speaker tracking so the subject stays centered in the vertical frame.