Adds a video speed slider to lesson pages
या स्क्रिप्टच्या अशा आवृत्त्या ज्यांत कोड अपडेट करण्यात आले होते. सर्व आवृत्त्या दाखवा.
Remove "Playback" from label, as it was causing the element to jitter on Chrome-based browsers.
Made the slider only visible when the video is visible
