Posted this on wtw so posting it here as well for people.
If anyone is curious, you'll need to pay about 1500 yen from what I saw because the points system is 500 -> 1000 -> 2000 etc. No exact numbers.
Also the points page is only working when the language is set to 日本語 for some reason. I don't really understand the error message when the language is set to English. /shrug
Stream seems to start at about 9am BST (6 days, 18 hours from time of posting). Like already mentioned, parts of the stream will be free. I'm guessing the PV will be free but the concert/performances will be paid. (could be wrong but I'd say it's a good assumption if they plan on getting an English version of the PV up again soon afterwards like with the teaser) (edit: plus from the looks of it on the actual website, it's written with Guest Talk show first then the PV and then the performance so it'd make sense for the first half of the stream to be free, the second half paid for)
Also it's only day 2 being streamed. Day 1 will have (for those curious):
Wormmon & Vmons VAs will be there.
Showings of Digimon: Our War Game and Diablomon's Counterattack (aka Revenge of Diaboromon)
Guest Talk Show
Guest Q&A session
Promotional Item presents lottery (I think it says)
Big surprise news