Greasy Fork

var fail = 0; This is never incremented.

Here is some revised code:

(function() {
    'use strict';
    var link;
    var fail = 0;

    const log = (str) => console.log(`[CDL] ${str}`);

    function geturl() {
        link = document.querySelector(".video-player__container > video:nth-child(1)")?.getAttribute("src");
        if (link === null || link === undefined) {
            log("waiting");
            if (fail < 5) {
                fail++;
                setTimeout(geturl, 500);
            }
        } else {
            log("found clip link")
            link = link.replace(/\?.*/g, "");
            log(link);
            document.querySelector("div.clips-watch > div.tw-animation > div.tw-c-background-base")?.insertAdjacentHTML('afterend', `<div><a class="tw-align-items-center tw-align-middle tw-border-bottom-left-radius-medium tw-border-bottom-right-radius-medium tw-border-top-left-radius-medium tw-border-top-right-radius-medium tw-core-button tw-core-button--primary tw-inline-flex tw-justify-content-center tw-overflow-hidden tw-relative" href="${link}" download>Download Clip</a></div>`)
        }
    }
    if (document.readyState === "complete") {
        geturl();
    } else if (document.readyState === "interactive") {
        // DOM ready! Images, frames, and other subresources are still downloading.
        geturl();
    } else {
        // Loading still in progress.
        // To wait for it to complete, add "DOMContentLoaded" or "load" listeners.
        window.addEventListener("DOMContentLoaded", () => {
            // DOM ready! Images, frames, and other subresources are still downloading.
            geturl();
      });
    }
})();