YouTube
CS50 Subtitles: Watch CS50 in Your Own Language
CS50 lectures come with English captions. How to get CS50 subtitles in German, Arabic, Chinese, Dutch, Italian or Portuguese, with English kept on screen.
Online courses
2 articles on the InterSub Blog.
Online coursesCoursera Chrome Extension: 6 Picks for Coursera and Udemy
Six Chrome extensions for Coursera and Udemy: speed, focus, notes, reading help and translated subtitles, plus what both sites already do without extensions.