How to Add Overlay & React to Another Video

Reaction videos are everywhere right now — someone’s face pops up in a corner or side panel, reacting in real time to whatever’s playing in the main clip. It’s a simple trick once you know the layout, and it works for commentary, comedy, or genuine reactions to trending content. This guide walks through the exact steps to build one yourself.

We’ll use CapCut for this, since it’s free and handles overlay layering well, but the same core idea applies in most other video editors too.

What You Need

• CapCut (free, iOS/Android/desktop)
• The main video you want to react to
• Your reaction footage — either recorded live while watching, or filmed separately and synced afterward
• Rights to use the original video — see the note on permissions below before publishing

A quick but important note: reacting to someone else’s content publicly can raise copyright and platform-policy questions depending on how much of the original clip you use and where you post it. Many platforms allow reaction content under fair use or their own reaction-content policies, but always check the specific platform’s rules, and favor using shorter clips of the original alongside substantial original commentary of your own.

Step 1: Import the Main Video

Open CapCut, start a new project, and place the video you’re reacting to on the main timeline. This becomes your background layer — the content your viewers are watching.

Step 2: Add Your Reaction Footage as an Overlay

Tap the plus (+) icon to add your reaction clip as a separate overlay layer above the main video, rather than placing it on the main timeline.

Step 3: Resize and Position the Overlay

Drag and resize your reaction clip into a corner or side panel of the screen — bottom corners are common for reaction content since they don’t block key visuals in the center of the main video. Leave enough of the main video visible so viewers can still follow what’s happening.

Step 4: Sync the Timing

Line up your reaction footage with the moment in the main video it’s responding to. Scrub through both clips together and nudge your overlay’s position on the timeline until your reactions line up naturally with what’s happening in the main footage.

Step 5: Add a Frame or Border (Optional)

To make the overlay visually distinct from the background video, add a simple border, rounded corners, or a colored frame around your reaction clip. This is a small touch, but it helps viewers instantly tell the two videos apart.

Step 6: Adjust Audio Levels

Reaction videos usually need both audio sources — the original video’s sound and your own reactions/commentary. Lower the main video’s volume slightly during moments where you’re actively talking, so your voice stays clearly audible without completely muting the original content.

Step 7: Add Captions or Commentary Text (Optional)

Adding on-screen captions of your key reactions or thoughts can boost engagement, especially for viewers watching with sound off. CapCut’s auto-captions feature can generate these quickly from your spoken audio, which you can then edit for accuracy.

Step 8: Export Your Video

Once everything is synced and positioned, export at your platform’s recommended resolution and aspect ratio (commonly vertical 9:16 for TikTok and Reels).

Once you’ve built one reaction video, the workflow becomes fast to repeat — the overlay positioning and sync process is really the same steps every time. If you want to explore other editing tricks like this, our Graphics, Design & Creativity section has more tutorials in this direction.

How to Fix Common Problems

Reaction and main video feel out of sync: Zoom into the timeline for more precise adjustment, and nudge your overlay clip frame by frame if needed.

Overlay is blocking important parts of the main video: Reposition it to a less critical corner, or shrink it slightly.

Audio is a messy mix of both clips: Manually adjust volume levels at specific points rather than using one flat volume for the entire main video track.

Video gets flagged or removed after posting: Review the platform’s specific reaction-content policy, and consider using shorter original clips paired with more of your own added commentary.

Frequently Asked Questions

Do I need permission to react to someone else’s video?

It depends on the platform and how the clip is used — many platforms have specific reaction-content allowances, but it’s worth reviewing the relevant policy rather than assuming, especially for monetized content.

What’s the best overlay position for a reaction video?

A bottom corner is most common since it keeps the center of the main video visible, but this can vary depending on where the important action happens in the main clip.

Can I do this on mobile only, without a computer?

Yes, CapCut’s mobile app supports the full overlay and sync workflow described here.

Should I record my reaction live or separately?

Live works well for spontaneous, authentic reactions but takes more editing to sync. Recording separately gives you more control but can feel less natural if not synced carefully.

How do I keep both audio sources balanced?

Adjust volume levels manually at different points in the timeline rather than relying on one static volume level for the whole video.

Conclusion

A good reaction video comes down to clean overlay positioning, tight timing sync, and balanced audio — once those three things are in place, the format is easy to repeat for new content. Reading through the steps gives you the process, but the video below shows exactly how the overlay, sync, and audio balancing come together in real time.

Watching this built from start to finish will save you a lot of guesswork compared to figuring out the sync and audio balance entirely on your own.

Have a question, or run into an issue building your reaction video? Drop it in the comment box below — we read every one — or reach the DCL Admin directly through our Contact Us page.