Load a video, choose the part you want on the filmstrip, and export just that part. Click the middle of the screen to pick a file, or drop a video anywhere on the page.
The handles at the left and right of the filmstrip are the in and out points. Drag them to change the range, or click along the strip to jump to that moment. I and O set the in and out points at the current position, the arrow keys step one frame at a time and one second with Shift, Space plays and pauses, L loops the range, and M turns the sound off and on.
Exporting records the selected range in real time from beginning to end, so a long range takes just as long, and pressing the button again stops it. Finished clips line up below, five at most; click one to play it, and use the two icons in its corner to save or delete it.