Hello community,

I also posted my solution/problem analysis in THIS THREAD

Problem Description:
A) Your USB webcam works fine in other applications and in the Skype Options Video Preview
B) Your webcam has a built-in microphone (in my case it shows as "USB Audio Device" in my Windows XP device manager)
C) when you start a video call, your webcam will become active (green light) and the microphone works - but video does not. You only see a black screen in your video preview and the person you are calling also sees only a black screen.
D) You either use a USB headset/microphone or have previously plugged in some other USB audio device/microphone into your computer.

Solution/Possible workaround:
even if you are not using the other USB Headset/USB Audio Device you installed at some point earlier anymore - try plugging it into your computer again and try video calling again.

In my case, I was using a Labtec Webcam 2200 and a Logitech Clearchat Comfort USB headset. For me video will only work if I have both the webcam and the headset plugged in. As soon as I unplug the headset video will no longer work.

This is definitely a driver problem. There must be some kind of conflict with USB drivers for audio and video and skype. I am not an expert - but if I was I would try to uninstall all USB devices that have been installed in the past and that are not in use anymore. (USB flash drives, USB audio devices, USB connections of digital cameras, and so forth). Anyway, my video calling works now - but only if I leave my USB headset plugged in as well as my webcam - even though I do not use the headset but the built-in webcam microphone and the standard sound output for skype.

Hope I could provide at least some help. Maybe Skype developers even read this thread and use the information provided to improve skype in the future...