The Royal Opera House - The Royal Opera House launches a programme of free online content for the culturally curious at home
The Met Opera is streaming titles from its "Live in HD" series through its website. A different opera every day available for 20 hours.
The Ring Cycle (Opera North) to occupy hours and hours and hours and......Opera North has also put on line The Turn of the Screw (Opera North) which will be available until 21 August 2020.
From the Royal Ballet comes Mayerling (The Royal Ballet)
Teatro La Fenice in Venice is putting on-line some of their operas. See https://www.teatrolafenice.it/en/stay-at-home-at-home-with-la-fenice/
Also from Italy Teatro dell'Opera di Roma is providing opera and ballet performances
The Mariinsky Theatre in St Petersberg has just started a series of on-line broadcasts of opera, ballet and concerts. Click on Mariinsky.TV — live webcast. Also from Russia the Bolshoi is presenting a series of their Cinema Broadcasts for free: https://youtube.com/user/bolshoi