Khan academy translation/localization tips

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.
- Prepare a mask image using Photoshop/Gimp.
- Use camtasia, import the mask image and overlay.
Here is a YouTube video: How to overlay your local language text on top of English original video

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.
Solutions
- Use bookmarklets
- If a bookmarklet doesn't work, simulate it manually. Instruction slides.
  1. In a translation dashboard, at the crowdin window, jump to the corresponding Crowdin page.
    - (Recommend to use Group by pattern)
    - Click context
    - Click file to jump to the Crowdin
    - Choose proofreading mode
  2. In a translation dashboard, at the crowdin search window,
    - Use metadata to filter (Bookmarklet)
    - Use keywords to filter (as you like)
Here is a YouTube video: How to jump from a Khan academy Translation Dashboard page to Crowdin to approve the many strings at once

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.
Solution
- Instruction slides.
- Separate the audio track (as mp3 file) from video (mp4) using VLC player.
- Use audacity, process effect, vocal reduction and isolation tool.
- (Extension. If you need to process thousands files, VLC player has a Lua interpreter, Audacity supports a macro. Thus, you can automate the process. But I muself have not tried yet.)
Here is a YouTube video: How to remove voice from the audio track in the video.