* 1-hour videos are a bit faster to render server-side and don't
require so much index data to be transferred before play starts
* the timestamp tracks might be causing a lot of excess data transfer
in some cases. They're currently not interleaved by ascending
timestamp, and I wonder if they should be. Chrome might be pulling
all the bytes between the current position in the two tracks, which
can be excessive. I'll have to consider interleaving when I add
audio anyway. But for now, just make the default UI display
snappier. Chrome doesn't display the timestamp track anyway, so
don't let it slow things down.
Once I have more than one area of the UI (e.g., adding config, live
video, or a scrub bar prototype), I'll use this for a pull-down menu to
go between them, and maybe add a filter icon to do what this does. But
this works for now and most closely matches the old UI.
I tried to use a Collapse or Slide transition, but I had trouble getting
it to work on both desktop and mobile. In particular, the way I used the
flex wrap to display the selectors on the left/above doesn't seem
compatible with picking an orientation. If I pick the wrong orientation,
the list views won't fill the empty space.
