Instant beats uploading — by minutes
Upload-based trimmers spend their time moving your file: a 300 MB recording uploads for minutes before any work starts. Here the file opens directly in your browser, and Instant mode copies the compressed stream untouched — the cut takes under a second whatever the size, with zero quality loss, because nothing is re-encoded.
The keyframe trade-off, honestly
Stream copy can only cut where the video has a keyframe (typically every 1–5 seconds), so an instant cut may start slightly before the frame you chose. For most jobs — dropping the fumbling at the start of a screen recording, sending just the relevant minute of a meeting — that is invisible. When the exact frame matters, Precise mode re-encodes the kept part frame-exactly at near-transparent quality. Cut first, then feed the result to Compress Video or Video to GIF — trimming is the cheapest size reduction there is.