(For those unfamiliar with bilibili, hit the blue toggle underneath the video, in the middle, to get rid of the comment crawl.)
The highlights for me are the first full animation starting at 4:57 (Venti's trailer theme still freakin' slaps); the musical medley starting at 14:43 that features the collaboration of all number of internet musicians including some of my favourite YouTube talents HuskybytheGeek and Alex Moukala and many others; and the Perpetual Mechanical Array fight starting at 32:21 that sees a fan animation group trying their darndest to be UFOTable. Stop-motion Ayaka vs. watermelon slime at 55:39 is cute. Childe vs. Zhongli ala Kamen Rider at 58:48 is awesome, but I need subtitles. Some great artwork for the piece at 1:17:00 that re-frames the Act III story from Kazuha's point of view (spoiler alert for those that haven't finished the Archon Quest). Oh, and of course the ending video is what it is. I should've guessed. Not that I'm complaining. One of the greatest anime end credits ever.
Unfortunately, the more comedy-oriented bits fall flat for me at points until I see a subtitled version of this stream.
Time stamps for all the various bits are all in the top comment.