Step 1: get the footage into a scannable shape
CCTV systems export folders of small clips. Either scan them one by one, or concatenate first with ffmpeg: list the files in order in a text file and run `ffmpeg -f concat -i list.txt -c copy full.mp4`. The copy codec keeps it fast and lossless. One continuous file scans more coherently than forty fragments.
Step 2: scan for activity windows
Open the Motion Scene Scanner, load the file, and press Scan. It steps through the video one second per sample, measures frame-to-frame change at reduced resolution, and collects the stretches where change stays above threshold. Start at Medium sensitivity; the result is a short list of windows with peak thumbnails instead of a timeline.
Step 3: review the windows, not the video
Work down the list and press Jump on each window — the preview seeks straight to the moment. Most windows are nothing (a shadow, a bug on the lens, compression shimmer); you clear each in seconds. The suspicious ones get notes with their exact timestamps. This is where 20 hours becomes 30 minutes: you only ever watch the segments where the picture changed.
Step 4: capture the frames that matter
For any window that matters, open the Timestamp Frame Grabber and type the moment — 14:32.7 — to export a clean full-resolution still. Timestamped stills are what incident reports, insurers and police actually file. Keep the original recording untouched; the timestamp lets anyone regenerate the still.
Why this is safe for sensitive footage
Surveillance exports are exactly the material you cannot upload to a random web service — they show homes, faces, plates, schedules. Every tool in this workflow processes locally: the browser decodes the file on your machine and nothing is transmitted. You can disconnect from the internet after the pages load and the whole pipeline still works.
Known limits
Change-detection is not understanding. It cannot tell a person from a tumbleweed, and it can miss slow or gradual events that never cross a per-second threshold. Treat the scan as an index of where to look — the judgment stays with you, which is as it should be for anything evidence-adjacent.