As the title suggests, It’s a webhook that Plex connects to send various events on my Plex Account (when watching a tv series or movie). For more information about Plex Webhooks
If you need someone to test this feature. (if you are planning it to do). I can volunteer. 
This would be great to have!
+1 i would like this too
Hello, is this feasible on app? Like a premuim user feature? Thank you!
At this point SeriesGuide does not really have a web service, which would be required to allow the Plex server to send events to it.
As an alternative, if you have SeriesGuide connected to Trakt, they have a Plex scrobbler: https://trakt.tv/settings/scrobblers
For now as Trakt stops to provide webhooks or api access for nonVip members, maybe its good time the Seriesguide team to integrate the webhooks please? 
