Requires that ffmpeg is available on your system path.
Arguments
- video_file
- string: path to the video file 
- debug
- logical: if - TRUE, echo the ffmpeg output to the console
Examples
if (FALSE) {
  newfile <- ov_set_video_meta(ov_example_video(), comment = "A comment")
  ov_get_video_meta(newfile)
}
