If you've seen Ajay's video, you've probably got a pretty good idea of how this movie goes. However, I have a source who has watched the movie and who is also quite fluent in Japanese. Since Ajay posted his summary quickly, that gave me some freedom to take my time and undertake a major interrogation, and therefore my summary should offer significantly more in the way of context, clarification, and sometimes even outright correction to the account you already know.
This summary is in fact so thorough that it is too long for Reddit by a lot. Rather than put part of it in the comments (and making everyone scroll through all that every time they want to join in the discussion), I've made a Wiki page.
Plus, the text contains links to gifs from all three trailers, the three trailer-based PVs, and the premiere cast introductions, along with links to character designs, settings, items, and other promotional materials when they are referenced, in the hopes that it will give you a fuller picture of how this movie looks and where exactly each trailer scene occurs. It's especially nice if you're not on mobile and you have RES, which embeds images and clips.
That said, not a single image of Gogeta has leaked (if you've seen one, it's almost certainly fake; tag me in the comments if you're not sure), and his portion of the movie was barely used in promotional videos, so there's a big gap in the last 1/5 or so of the movie, image-wise. Tag me also if you notice any mistakes or have any questions.....