Kopete supports yahoo webcam and it works seamlessly. Although it doesn’t work right away after installing kopete. If you try to access anyone’s webcam you’ll get the following error.

Unable to find the Jasper image conversion program.
Jasper is required to render Yahoo webcam images.
Please see http://wiki.kde.org/tiki-index.php?page=Kopete%20Webcam%20Support
for further information.

You can fix it simply by installing jasper packages available in Ubuntu repositories:

sudo apt-get install jasper libjasper-java libjasper-runtime libjasper-dev libjasper1

You can now send and receive anyone’s webcam.

Cheers!