The opening part of the AMV (after the initial drum intro, like first two seconds, I chose random scenes across the 11 episodes) was actually the opening of the anime itself. I cut it up and sped parts of it up in order to maximise sync both external and internal, but you're definitely right, it was an opening sequence.
I also agree with you that the first minute or so is particularly strong compared to the rest of the video. There are two reasons for that; the first is that the portion which was stronger was edited prior to godix's death, and he was my main beta tester. I think I really missed his input in the second half of the video. The second reason is that as I continued to edit, with 11 episodes only and long, slow, static scenes, I began to run out of footage. By the end of the video (and on a convention deadline no less, but as you see, I took two awards out of the four conventions to which I sent it) I was really fighting to to finish the timeline.
I should have gotten rid of the black border on the blur. The blur beat is the only beat of that type in the entire song, so therefore, only one blur. The white flashes were not orphan frames or improperly rendered crossfades, they were intentional. I actually had more, but Ellen (MoonlightSoldier) successfully argued me out of keeping several of them. Perhaps I should have dispensed with all.
Also, the transition from the snow to the flowers is the actual end of the last episode. Again, I just edited it a bit and tweaked the speed to have it match the tempo of the song.