I made a similar post in the past that work with userstyles.org but now i just upload my first Firefox extension for Youtube, Afreecatv.com & Twitch.tv
The addon will hide the video lengths, progress bar and times.
Are you Tired watching e-Sport videos and already know the result of the match? Hide the video lengths, progress bar and times with this extension and enjoy your videos of online games or movies.
Works for: Youtube, AfreecaTV & Twitch.
I hope you enjoy it