Drop in a clip and a filmstrip appears under the player. Drag the handles or type the start and end times; arrow keys nudge a handle by 0.1 s, or by a second with Shift. “Play selection” lets you check the cut before you save it.
By default nothing is re-encoded: the picture stays exactly as it was and even long recordings are cut in seconds. The catch is that the start snaps to the nearest keyframe, usually within a second or two. Tick “Frame-accurate” and the cut lands exactly where you put it, at the cost of a quick H.264 re-encode.
Reads MP4, MOV, WEBM and MKV, plus AVI, WMV, FLV, 3GP and MTS (those go through the server). You get an MP4 that plays everywhere; WEBM stays WEBM.