Motivation: When you want to use Khan academy English original video, but you want to use your local language text, you can use overlay.
Method: Here I use Camtasia video editing.
Motivation: Jump from Khan academy TD (Translation Dashboard) to Crowdin to approve many strings at once. Crowdin has multiple strings approve method, but TD doesn't have.
Motivation: I work on a video voice over for KA videos. When the original audio track is music + voice I only want to remove voice.