Why I can't trace linux process's childs with truss?

[Yuri]

I am trying to get the log of all system calls that skype makes with 
truss -f /usr/local/share/skype/skype
For some reason the resulting log only has the leading process calls and 
nothing from it's 8 childs.
Truss doesn't show any 'cloned' processes. Is this a bug in truss that 
it doesn't follow 'cloned' processes?

Is there any workaround or other way I can debug skype? strace doesn't 
work on amd64.
I am primarily interested why it can't read /dev/video0 device, created 
by webcamd.

Yuri