iTunes U downloads not added properly

Question

I am trying to download several iTunes U lectures from Walter Lewin's 8.01 Classical Mechanics series. I "GET" all the lectures I want to queue them up overnight.

My problem is that when they all finish downloading, they don't get added properly to their corresponding iTunes U series. In this case, I should expect to find them in
../Music/iTunes Media/iTunes U/Physics I_ Classical Mechanics

Instead, they all get stuck in
../Music/iTunes Media/Downloads/iTunes U/<lecture title>.tmp/download.mp4

As such, in my iTunes U window, these lectures are all grayed out as though they haven't been downloaded yet.

Attempted solution 1

1. I rename the download.mp4 into the correct lecture title format.
2. I add it to ../Music/iTunes Media/iTunes U/Physics I_ Classical Mechanics.
3. I restart iTunes.
4. It fails. The corresponding lecture is still grayed out.

Attempted solution 2

1. I rename the download.mp4 into the correct lecture title format.
2. I add it to ../Music/iTunes Media/Automatically Add to iTunes.
3. Instead, the file is immediately transferred to the Not Added folder.
4. In the iTunes U window, the corresponding lecture is still grayed out.

Attempted solution 3

1. I try to use File > Add to Library... and choose the downloaded lecture.
2. Nothing happens. No "Adding to Library" progress bar or anything. The corresponding lecture is still grayed out.