The data Twitch gives you
Every Twitch VoD has a `recorded_at` timestamp on its metadata: the exact UTC moment the stream went live. Two VoDs that aired concurrently have known clock offsets, which means you can align them in absolute time without any clap-sync or audio-fingerprinting step.
The math is trivial: pick the later `recorded_at` as t=0, offset the earlier stream by the difference. Both timelines now share an origin.
Finding overlapping windows
Given two or more aligned VoDs, the overlap window is the intersection of all individual stream durations on the absolute clock. Stream A from 18:00–22:00 UTC and stream B from 19:00–21:30 UTC overlap from 19:00–21:30.
This is the window you can edit collab clips in. Outside it, only one POV exists, so it is not a collab section. Most multistream editors expose the overlap window as a draggable region on a combined timeline.
POV swap cuts
The classic collab edit move is the POV swap: a clip cuts mid-action from one streamer's screen to their friend's screen reacting. This requires the two POVs to be aligned to within frame-accurate offsets, which requires aligning to within ±33ms for 30fps content.
Twitch `recorded_at` is second-precision, not millisecond-precision. For frame-accuracy you need a secondary alignment step: audio fingerprinting (cross-correlation on the audio waveforms) or a known event in both streams (a clap, a shared sound effect). Most multistream editors run an audio sync as a confirmation step after the recorded_at coarse alignment.
Chat across multiple streams
Chat from two collabing streamers is a useful signal: a moment that spikes in both chats simultaneously is almost certainly a clip. Filtering by "both chats peaked within 3 seconds of each other" finds the genuine collab moments and excludes the moments where only one chat noticed.
Combined chat-activity graphs (sum or product of the two streams) are the cleanest way to visualize this. Tools that show two separate graphs side-by-side make you do the correlation by eye, which is slow.
When recorded_at is wrong
A small percentage of Twitch VoDs have a `recorded_at` that is off by 30–120 seconds, usually due to stream-recovery interruptions where the recording stopped and restarted. If your initial alignment looks wrong by a constant offset, this is probably the cause. Apply a manual offset to compensate.
This is rare enough that most editing tools do not handle it automatically, but common enough that any serious multistream editor exposes a manual offset slider.