The player stepped to the next item in its own state while the history entry still held the item it
opened with, so F5 restarted the first episode. The player now says every item it moves on to, and the
page rewrites its entry with it (useHistorySubview's `follow`: no navigation, the overlays over the
player stay open, and the entry under an overlay is rewritten when a step lands back on it). The
player's URL is the item playing (`?v=player:<id>`), so a bookmark opens it; the list it plays from
stays in the history entry.