dropout-progress

Keeps track of:
Which season you are currently watching,
which episodes you have already seen in a season, and how far you've made into a given episode.

NB: The extension can only track your progress since installation.
That it, progress you've made before installing this extension will not be displayed.
Unfortunately I don't see this changing in future versions.
However, clicking the dropout-progress menu in the season listings will let you mark a season as watched at a time!

Changelog:
v 3.0.1 Fix bug where importing with overwrite could not remove season episode progress.
v 3.0.0: Add extention options page, allowing import/export of stored progress to file (this is helpful if, for example, you are switching to firefox)
v 2.2.0: Hide the new built-in vimeo OTT progress bars.
v 2.1.0: Fix name on season-control dropdown. More frequent time-sync to chrome profile.
v 2.0.0: Add season-control dropdown to allow marking a season as watched or new
v 1.2.0: Only blackout episodes that have been at least 94 percent finished. Also some style improvements