How this video trimmer works
Trimming means keeping one stretch of a video and discarding the rest. You set a start and an end with the two handles on the timeline, and VimCut produces a new file that contains only that selection. The original file on your device is not changed.
When your browser supports it, the trim uses the built-in hardware video encoder, which is fast. Otherwise it falls back to WebAssembly (ffmpeg.wasm), which is slower but gives the same kind of result. Either way the selection is re-encoded into an MP4 with H.264 video and AAC sound. Press play to preview exactly the selected part before you click Trim Video. You can loop the preview to replay the selected part while you decide. The start, end and length of the selection are shown under the timeline, so you know how long the finished clip will be.