Episode 7 deals with the Yamato passing the boundary of the Heliosphere and the crew saying their goodbyes to their loved ones back home. Yuria on the microphone might just be her taking her turn.
Interesting points on those previews (besides the amazing visuals):
-Ep04:
An Aurora on Saturns south pole, wonder if that is just for spectacle or it will play any relevant part on the story...
Kodai, Yuki, Analizer and Makoto seem to be aboard a Cosmo Seagul, good to finaly see it in action.
Wonder if that Gamilas peeking through the Yukikazes ports over Yuki is an actual soldier or an android like the upcoming Orta?
It seems that hole in the Cosmo Zero's nose isn't there just for looks as it fires a shot. Maybe a larger projectile, like a grenade...
The geisers of Enceladus in action... cool
We finaly get to see the new side-arms. They seem more compact that the original Cosmo-Gun. And Kodai now uses his brothers gun.
-Ep05:
The Reflexion Satelite Cannon firing is just a beautiful thing to behold.
The satelites seem to use energy field to deflect the energy, much like its been discussed on the previous comments. This was always implied but the actual animation made it seem like the beam would actually be bounced off the satelites. Here we see the field deploying just before the beam hits.
We see the crew in a room. In the original they went to the 3rd bridge (only time they actually gave it a purpose and a use, besides "Resurrection") but that was only after the Yamato had sunk and was upside down. So this might be an actual CIC.
The fighter launches are awesome. And the whole squadron flying in formation towards what i believe is Charon ... just beautiful stuff.
The Reflex beam hiting the shields... we get a sense of how powerful that thing is and how resilient the Yamato is, despite the massive blast. Without those shields i believe the Yamato would have been finished right there. Let the battle of wits begin.
-Ep06:
This time we have a frozen ocean with a big hole where the Yamato and the subsequent Reflex Gun shot opened a big hole. The Yamato is still upright, like in the original, where Okita ordered the ship be turned upside down just as a way to trick the Gamilas. And the depth charges just like in the original, too.
Kato loosing a pilot and being pissed off at it.
The Yamato tracking the satelite's positions. Are they keeping an eye out for the next shot or locking on to destroy them?
Kodai and Akira fly in the Zeroes through some sort of light barrier. The afore mentioned cloacking device barrier, perhaps?
The Yamato releasing balast to surface. It's on!!!
-Ep07:
The first few shots are from either the credits sequence or previous episodes, like Kodai and Okita looking at Mars. The shot of Nambu with the goggles, wich made you believe that the WMG will be fired is from episode 3. (though i havent seen that one yet, that image is on the new Yamato Crew Chapters 1 and 2 Digest Clear Files, on the sequence related to that episode). The next few shots of the crew are from the actual episode. There is one interesting shot of Yuki wich looks like the one in the opening sequence but this is longer. This makes me believe that at least part of the opening sequence scenes will be used in the episodes.
Why so much stuff from other sources instead of episode 7? One possible explanation, and this is just me talking, the next chapter will only come out in October, almost four months after chapter 2. Maybe not enough of episode 7 was ready in time for the volume 2 release so they went with it this way. Or the episode features scenes from what came before (maybe crew members telling their families what they've already been through, though i doubt they would use the little time they have for that). I would keep an eye out for the episode 7 preview in the retail version or in the 2013 TV run. XD