Hello and welcome to BBB Randalthor! Glad you found the forums here. I know a wee bit about WLM and webcams...and I'm hoping I can get you fixed there. YH can be a bit trickier but I'm hoping with these steps you'll be up and running in no time.
I have several Logitech cams and they work fine with both messengers. First, make sure you've installed the QuickCam software as well as the drivers. You can adjust some of the cam settings there, as well as set it up to use one or the other of the messengers as your primary (but that does not stop you from using it on either one.)
You still need to do the webcam setup in WLM under Tools/Audio and Video Setup on the WLM menu before trying to use the cam. You also have to set it up in YH as well. Please note the BETA version 9 of YH does not yet support video, so if that's the version you downloaded, you'll need to downgrade.
Now for the fun part. In order for Voice and Video to work properly on WLM you really nned to enable UPnP. If you go to Start/Control Panel/Administrative Tools/Services and make sure your SSDP Discovery Services and Universal Plug and Play Device Host are set to Started and Automatic. Alternatively, you can go to
Unplug'n'Pray and download small utility that (if saved to your desktop) will let you turn UPnP on/off. It can take a bit for your system to recognize you've enabled this if it was not on, so be patient. You can test it in WLM by going to Tools/Options/Connection and see if the status says "...you are connected to the internet through a UPnP port...."
Hopefully this will help you out! Let me know if it doesn't fix the problem.
-Doris-