Video for PowerPoint

  1. Open a Terminal/Command Prompt window
  2. Change to the directory with your source video
  3. Use the following command:

ffmpeg -i INVIDEO.MP4 -b 8000k -vcodec wmv2 OUTVIDEO.WMV

You must leave the outpt format as WMV, this is the best format to embed with PowerPoint. The INVIDEO.MP4 can be any format, any extention (eg INVIDEO.MOV, INVIDEO.AVI, INVIDEO.MPG). Youtube videos can also be converted (INVIDEO.FLV).
You can increase or decrease the - b 8000k number if you want to improve quality or decrease size. You can combine this with cropping by adding the cropping flag, read more here.