To be able to use a webcam on Linux, TeamTalk must be started with

LD_PRELOAD

and a V4L1 compatibility library.

In order to do that, change the last line in run.sh:

LD_PRELOAD=/path/to/v4l1compat.so ./teamtalk4

On a Ubuntu 12.10 amd64 change the line to:

LD_PRELOAD=/usr/lib/x86_64-linux-gnu/libv4l/v4l1compat.so ./teamtalk4

The file v4l1compat.so belongs to the package libv4l-0. Install it if the file does not exist yet:

sudo apt-get install libv4l-0

Found the solution [http://www.bearware.dk/phorum/read.php?1,2198 here].