Uses `<` and `>` to change the playback speed (defaults to 1.5x)

viki-playback-speed.js

((_w) => {
    const _d = _w.document;
    if (!_d.querySelector('#speeder')) {
        const getSpeed = s => s/10
        let speed = 15;
        let speedEl = document.createElement("span");
        speedEl.id = 'speeder';
        speedEl.innerText = ` ${getSpeed(speed)}x`;
        _d.querySelector('#channel-link > span').appendChild(speedEl);
        _d.querySelectorAll('video').forEach(v => v.playbackRate = getSpeed(speed));
        _w.addEventListener('keydown', (e) => {
            const {key} = e; 
            if( ['<', '>'].includes(key)) { 
                if (key === '<') speed -= 1;
                if (key === '>') speed += 1;
                speedEl.innerText = ` ${getSpeed(speed)}x`;
                _d.querySelectorAll('video').forEach(v => v.playbackRate = getSpeed(speed))
            }
        })
    }
})(window);