code: public static Observable<Bitmap> getVideoThumbnail(final String filePath) {
      return Observable.fromCallable(new Func0<Bitmap>() {
        @Override
        public Bitmap call() {
          return ThumbnailUtils.createVideoThumbnail(filePath,
              MediaStore.Images.Thumbnails.MINI_KIND);
        }
      });
    }
docs: /*
  Get video thumbnail from a video file, by path.