Well, I'm still banging away at this.
It turns out the video is not the (only) problem after all... I'm still getting the incomplete load behavior sometimes, even with the video player removed.
The browser's telling me there are items remaining to be loaded, so this
[i]...do some stuff here...[/i]
is never called. I'm getting that message even if everything on the page did, in fact, apparently load. Is there any way to tell what mysterious files IE is waiting for?
What I'm doing for the time being: a couple of no-nos, but I'm at a loss for what else I can do short of a window alert that says: "Shame. You're using Internet Explorer. Stop that."