The units you have blocking the door could be one space closer to the enemy. Because of scrolling, I'm not sure if this would save or lose time.
You can win in 8 turns simply by moving Seth one space further on turn 3, then moving him as far as possible on the next 3 turns. Two enemies will be killed by counters rather than normal attacks (one on turn 3, and one on turn 5), but the middle area will probably be faster. If you want to break the silver lance under the same circumstances as the current WIP, you should equip it on turn 3 for this strategy.
I should probably say something about Vanessa's options. If/when she promotes, she'll need 85 additional lance exp if she plans to use Vidofnir (and get that ever-important 5% critical hit bonus). This may or may not require giving her a steel lance. If she doesn't reach S lances, you'll lose about 12 seconds by letting Fomortiis counter, and you would also need more manipulation for that battle. If you don't promote her at all (the animation takes about 20 seconds in FE7), killing Lyon in the final chapter will require a double critical from Seth with 2 more strength than he has now, and you'll lose 22 seconds because you would need to attack Fomortiis twice. Also, chapter 17 could be annoying without a promoted Vanessa, but I suppose you could use Myrrh under those circumstances.
P.S.: You don't really need to make your entire post a link.
I suppose I didn't even think of that option because that would require suffering an attack from the shaman. I guess that takes about the same amount of time as killing the shaman outright, though (unless he goes for Saleh, which is of course possible).
Bump. Haven't seen a post in here in a long time, and a fire emblem TAS that's 75% complete just has me begging for more.
I do have a bad habit of having good progress for a few chapters, then stopping for months on end.
The current route works fine without changing Vanessa's starting position. She may end up in the same space as Seth in the middle of turn 1 (depending on which character gets priority over the other in this game). It would have been faster to make Seth take Eirika during turn 2, because both Seth and Vanessa end up next to each other that turn. Alternatively, You can modify that route so that it uses the same number of turns, but doesn't require Tethys. It requires moving Seth's starting position 2 spaces forward and making him move his full movement range each turn (picking up Eirika on turn 1). If you choose the modified route, a silver lance would allow Vanessa to kill the mercenaries in one non-critical hit.
Also, Saleh seems to have a B in light magic, which is just enough for that Purge tome you picked up. Do you plan to use it?
Excellent. But do you mind posting the .vbm for individual chapters instead? I get annoyed having to fast forward through 90% of the vid to get to the new chapter(s). Anyway, keep up the good work, that was fast considering 16 was finished only a couple days ago.
Chapter 18: If you used two additional characters, there would be a lot less time spent watching eggs gain 5 HP. This may end up being worth it, but I can't be sure. Chapter 19: Short chapter, solid route, not much to say about this one.
On turn 2, simply drop Eirika on a forest, move Vanessa so Eirika won't get blocked, and manipulate a miss. Vanessa will be attacked by 3 wights and kill them all. Eirika will be attacked by Riev and the ranged attackers who went after Vanessa on turn 1. (The third mogall that appears to have attacked Eirika in the screenshot is actually a reinforcement.)
Turn 3 should be obvious.
Also, I should note that with this strategy, trading the Vidofnir to Vanessa can be done during the chapter itself instead of the preparations screen.