Guide

How to record the last 30 seconds on a Mac

By Dylan Buck ·

A player pressing a shortcut after a racing-game crash while translucent frames curve backward through the previous thirty seconds.

The important word is last. Apple's screen-recording tools can record the next thirty seconds, but a goal, win, or mistake is usually interesting only after it happens. Saving the recent past requires a recorder that was already keeping a temporary rolling buffer.

The Mac's built-in recorder cannot go backwards

Pressing Shift-Command-5 opens Apple's Screenshot app. It can record the whole screen, a selected portion, and, on macOS Tahoe 26 or later, a selected window. But Apple's own instructions still begin with choosing a mode and pressing Record. QuickTime Player's New Screen Recording command opens those same controls on current macOS releases. Neither tool has footage from before you started it.

That makes Screenshot and QuickTime good for a tutorial or a session you planned to capture. They do not solve “save what just happened.” For that, choose one of the three approaches below.

Option 1: Steam Game Recording

If the game runs through Steam, start here because it is free and probably already installed. Open Steam, then Settings, then Game Recording, and select Record in Background. Valve's Game Recording guide explains that the background recording is temporary: older footage is overwritten when the disk allowance fills, while clips you create from it can be saved permanently.

Steam is the best no-cost answer when all the games you want to capture are launched by Steam and you like its overlay and recording library. Its structural limit is also clear: Valve says Game Recording captures games played through the Steam client. It is not the same solution for an App Store game, an emulator, a browser game, or a title launched through another store.

Option 2: OBS Replay Buffer

OBS Studio has a genuine Replay Buffer. In Settings, open Output, enable Replay Buffer, set the maximum replay time to 30 seconds, then assign a Save Replay hotkey under Hotkeys. Start the Replay Buffer before playing; the save hotkey writes the recent window to a file.

On a Mac, select an Apple VideoToolbox hardware encoder rather than x264 when your recording format supports it. OBS's hardware-encoding guide documents VideoToolbox support on Apple silicon and Intel Macs. If forgetting to start the buffer is the problem, OBS also documents the --startreplaybuffer launch option.

OBS is the most flexible free option. It is also a broadcast application: you configure a scene, sources, output, encoder, audio, and hotkeys. That setup is worthwhile for streaming or multi-source production. If all you want is one shortcut that is already armed, it may be more interface than the job needs. Our OBS comparison covers that trade-off without pretending OBS is a bad tool.

Option 3: a dedicated rolling-buffer app

A dedicated Mac clipper reduces the workflow to selecting a game and pressing one shortcut after the moment. Hindsight keeps an encoded ring buffer in memory, continuously evicts the oldest samples, and writes an MP4 only when you ask it to save. Set the clip length to 30 seconds in Settings, then use the global shortcut inside the game.

Hindsight captures a window rather than requiring a game integration, so the same mechanic works for native Mac games, Steam, CrossOver, Parallels, browser games, and emulators. A window capture also keeps the desktop and notifications out of the file and can take the game's audio without the Discord call. It is a paid option after the 14-day trial; Steam and OBS are the honest free answers above.

Why a 30-second clip can be slightly longer

Compressed video cannot begin cleanly on an arbitrary frame. It has to begin on a keyframe: a complete image that the following frames can refer back to. Hindsight asks its encoder for a keyframe about every two seconds and begins a save at the newest keyframe at or before the requested point. A “last 30 seconds” file can therefore contain roughly 30 to 32 seconds. Starting on that boundary lets the app remux existing encoded frames instead of re-rendering the clip.

In the original Hindsight proof of concept, a 960×664 capture at 60 fps and 10 Mbps held a 30-second video ring in about 33 MB of memory. Saving the trailing eight seconds produced an 8.86-second, 10.7 MB file in well under a second. Those are development measurements, not a promise for every resolution and Mac; they are included to make the mechanism inspectable rather than calling it “lightweight” without a number.

Which method should you use?

Whichever route you choose, test the hotkey once before a real session. A rolling buffer can save only what it was configured and permitted to capture, and thirty seconds spent checking is cheaper than discovering that after the play you wanted.