Fast or precise?
Fast mode copies the video as it is, so it takes seconds and keeps the original quality, but the cut snaps to the nearest keyframe, often up to a couple of seconds early. Precise mode re-encodes to MP4 and cuts exactly where you asked; it is slower.
How to cut
1. Drop the video. 2. Pause the player where the clip should start and press “Set start”, then do the same for the end (or type the times). 3. Press “Cut video”.