We already knew that it was going to be broadcast in January, but now we know the date and time. We don’t know the length or amount of songs though, but as always, expect it to be missing a few songs. Expect a full DVD/Blu-ray to be released a few months later.
For those unaware of what WOWOW is, it’s a premium TV subscription in Japan with many channels. They have broadcast many BABYMETAL shows in the past, pretty much all future Blu-ray releases, as well as some festivals.
There is no free (and legal) place to watch it live. You can watch with a website/app such as For Joy TV, for a monthly cost (you can get it for 1 month, if you want).
Fans always record the show and share online within a few hours.