How to use
Step 1: copy the share link
Open the video in the Kuaishou app, tap Share, then Copy link. You get text containing a v.kuaishou.com short link.
Step 2: paste
Paste the whole text into the box. No need to trim it down to the URL.
Step 3: play or download
The video plays on the page after parsing; hit download to save the watermark-free file.