Reaction videos are one of the most reliable formats on TikTok, Reels, Shorts and YouTube: your face responding, in real time, to something happening in front of you or on a screen. The format looks effortless, but the thing that makes or breaks it is timing — your reaction has to line up with the exact moment you're reacting to. On iPhone there are two clean ways to nail that, and this guide walks through both.
What a reaction video actually is
A reaction video shows two things at once: the subject (a scene, an event, a video clip, a product reveal) and your reaction to it (your face, usually as a smaller inset). The classic layout is Picture-in-Picture — your face in a corner while the main content plays underneath. What viewers are really watching is the relationship between the two: the surprise, the laugh, the wince, landing at the right second. Capture the reaction separately and paste it on later and it never quite feels honest. The goal is to record your face and the thing you're reacting to together.
The two ways to make a reaction video
There are two distinct scenarios, and they use different workflows:
| You're reacting to… | Best method | Result |
|---|---|---|
| Something in the real world (a place, event, unboxing, prank) | Front + back at once (live PiP) | One synced take, ready to post |
| A video playing on a screen (a trailer, a clip, gameplay) | Face-cam recording + source clip in an editor | Combined in an app like CapCut or iMovie |
The important thing to understand up front: DualCam records the cameras, not your screen. So for real-world reactions it does the whole job in one take, and for screen reactions it records your reaction beautifully as a face-cam, which you then lay over the source clip in an editor.
Method 1: Real-world reactions with front + back at once
This is the fastest reaction workflow and it needs no editing. Apple's Multi-Cam system (iPhone XS and newer, iOS 17+) lets DualCam record the front and back cameras simultaneously: the rear camera films the scene in front of you while the front camera captures your reaction, shown as a draggable Picture-in-Picture inset.
- Open DualCam and grant camera and microphone access.
- Choose the front + back pairing — back camera on the scene, front camera on your face.
- Drag the PiP inset to a corner that won't cover the action.
- Pick your resolution and frame rate — up to 4K at 60fps, HEVC or H.264.
- Tap record once. Both feeds capture together, perfectly in sync. Swap which lens is the main view mid-take if you need to.
- Stop, and the take is saved to Photos — a finished reaction video with no editing required.
Because both cameras share one take, your reaction is locked to the moment that caused it. For a deeper look at this setup, see recording the front and back camera at the same time.
Method 2: Reacting to a screen with a face-cam + source clip
When you're reacting to a video — a movie trailer, a music video, gameplay, another creator's clip — the reaction and the source come from two places. Here DualCam records your face-cam (your reaction, with clean audio), and you combine it with the source clip in an editor:
- Play the clip you're reacting to on a second screen (a laptop, TV, or tablet) so you can watch and respond naturally.
- Record your reaction in DualCam as a face-cam take. Keep your framing consistent so it drops cleanly into a corner later.
- Open an editor like iMovie or CapCut and add the source clip on the main track.
- Layer your face-cam recording on top as a Picture-in-Picture inset, then nudge it left or right until your reaction lines up with the moment.
- Export, and you have the classic screen-reaction layout.
This is the same idea as building a split screen video — two feeds, arranged together — except one of them is the source clip rather than a second camera.
Framing and lighting tips
- Light your face. The front camera is the star of a reaction video and it's usually the darker feed — add a lamp or face a window so your expressions read clearly.
- Park the PiP where it won't hide the action. Drag your face inset to a corner clear of subtitles, scores, or the key part of the scene.
- Leave headroom. A little space above your head looks natural in the small inset and gives room for captions.
- Get your reaction in frame first. Check the PiP before you hit record — a great reaction cropped at the chin is wasted.
- Shoot in 4K. Extra resolution keeps your face sharp even when it's shrunk into a corner, and gives room to reposition later.
Vertical for TikTok, wide for YouTube
Reaction videos live on both short-form feeds and long-form YouTube, and they want different shapes. DualCam saves a 9:16 vertical file and a 16:9 horizontal file from the same take, so one reaction shoot fits TikTok, Reels and Shorts and the YouTube main feed without re-shooting. If you're deciding which to lead with, our guide to vertical vs horizontal video breaks it down platform by platform. When your wide cut is ready, DualCam's built-in YouTube upload lets you publish it without leaving the app.
Get started
Whether you're reacting to the world in front of you or to a clip on a screen, the recipe is the same: capture a great front-camera reaction, keep it in sync, and lay it against what you're reacting to. Download DualCam on the App Store and record your first reaction video today.