This version is broken. Please use 1.2.8 which is a patched version of 1.2.6.
Chrome: https://chrome.google.com/webstore/detail/mnjggcdmjocbbbhaepdhchncahnbgone
Firefox: https://addons.mozilla.org/addon/sponsorblock/
Changes this version:
Improvements to sponsor submission. There should be less bugs.
Added minimum sponsor duration option.
Added custom server support.
Fixed preview sponsors.
Added an option to not check for sponsors on unlisted videos.
Code-wise:
It is now written in TypeScript and uses webpack.