Inviduration (Source) shows total duration of playlists in Invidio.us web app/instances.
Try the addon here.
It currently works on these instances:
- https://invidious.snopyta.org/
- https://invidious.kavin.rocks/
- https://invidious.xyz/
- https://yewtu.be/
- https://invidious.tube/
Note: This add-on does not work for playlists with more than 100 videos because it queries the Invidio.us API for lengths of videos. View this issue.

- License: MIT License
- Weekly downloads: 0
- Average daily users: 4
- Rating: 0/5 of 0 ratings
- Created: 2021-09-17 08:23:43
- Last updated: 2021-09-18 08:26:12
- Homepage: https://github.com/rsapkf/inviduration
- Support site and email
- Orig: https://addons.mozilla.org/en-US/firefox/addon/inviduration/
- API: {a3705f80-7c7f-4f33-a9b3-d6e10ff44b81}