If you possess a file named "Outlander S04E12 libvpx," you likely have a capture of a browser stream. The quality is usually excellent, though sometimes slightly softer than a direct Blu-ray rip encoded with x264.
When Outlander is streamed on platforms like Netflix, Amazon Prime Video, or Starz, the service must compress the raw video file to send it over the internet efficiently. outlander s04e12 libvpx