Why does Ubuntu create at one day /dev/video0 and at another day /dev/video1?

[Detlef Lechner]

Hi,

last night my Karmic computer had a file /dev/video0. Today (after 
thawing) it does not have it any more but it has a device file /dev/video1.
Why does Ubuntu create at one day /dev/video0 and at another day 
/dev/video1?

Today '~$ xawtv /dev/video1;
This is xawtv-3.95.dfsg.1, running on Linux/i686 (2.6.31-14-generic);
xinerama 0: 1400x1050+0+0;
WARNING: No DGA direct video mode for this display.
can't open /dev/video0: No such file or directory.'
Why does this program tell me this? I've told it to use /dev/video1.
Next I created a softlink from video0 to video1. Now '~$ xawtv 
/dev/video1' does not report this error any more.

Regards
Detlef Lechner