If you see this string on a forum or hosting site, the tags provide technical information about the media:

This specifies the source of the recording. It was captured from a High-Definition television broadcast (like OCS in France or HBO) rather than a Blu-ray or a direct web stream (WEBRip). 3. Plot Summary (Spoiler Alert)

This indicates the audio track is dubbed in French, or the primary language of the release is French.

The phrase refers to a specific digital release of the fourth episode of the fourth season of the HBO sci-fi series Westworld .