This is where the "downloader" enters the equation. It is no longer a simple script. To download from KVS today, the tool must essentially become a headless browser.
You cannot download a single “KVS Player Video Downloader” app to use on every site. The download function only appears on websites built with the KVS script and configured to enable it. If you try to use it on YouTube or Vimeo, it won’t work. kvs player video downloader
Several third-party tools are designed to bypass the obfuscation used by players like KVS: This is where the "downloader" enters the equation