Qt Multimedia camera still doesn't work on Windows MSVC 2010 32-bit

The QML API for cameras doesn't seem to work with Qt 5.1.0 on Windows. For example, here's what happens with the declarative-camera QML Camera Example:

I open it in Qt Creator, and click the Debug button. The example compiles and runs, and then issues show up in the Issues tab:

warning: Exception at 0x75d1c41f, code: 0x406d1388: Startup complete, flags=0x0 (first chance)
warning: Exception at 0x75d1c41f, code: 0x406d1388: Startup complete, flags=0x0 (first chance)

The QML/JS Console gets a message, saying:

QWidget: Cannot create a QWidget without QApplication kernel\qwidget.cpp 1094

There is also a window from Microsoft Visual C++ Debug Library:

Debug Error!

Program:
…op_Qt_5_1_0_MSVC2010_32bit-Debug\debug\declarative-camera.exe
Module: 5.1.0
File: kernel\qwidget.cpp
Line: 1094

QWidget: Cannot create a QWidget without QApplication

(Press Retry to debug the application)

The buttons say, "Abort Retry Ignore"
I click Retry and it just quits.

The non-QML Camera Example worked. The QML Video Shader Effects Example crashes the same way, but if I click Run instead of Debug, and click Retry, then I get a standard Windows debug window that opens Visual Studio, with the call stack

Qt5Cored.dll!58bfecc1()
[Frames below may be incorrect and/or missing, no symbols loaded for Qt5Cored.dll]
kernel32.dll!75e114dd()
> msvcr100d.dll!_free_base(void * pBlock) Line 50 + 0x13 bytes
00189434()
00000004()
Qt5Qmld.dll!59c7fe7f()