Imagine a camera that only takes pictures one pixel wide. Now make it take a picture, for example, 60 times a second and append every pixel-wide image together in order. This is what's happening here, it's a bunch of one pixel wide images ordered by time. The background stays still as it's always the same area captured by that one pixel, resulting in the lines, but moving objects end up looking correct as they're spread out over time.

At first, I thought this explanation would make sense, but then I read back what I just wrote and I'm not sure it really does. Sorry about that.

No, thank you. This was perfect. It completely explains where the train comes from and where the lines come from.

Lightbulb on.

Aha achieved. (Don’t you love Aha? I love Aha.)

Yeah, like walking past a door that's cracked just a bit so you can see into an office only a slit. Now reconstruct the whole office from that traveling slit that you saw.

Very cool.

It made sense to me!