VLC doesn't support "h264" ... (and other codecs)
 

After upgrading to Squeeze (and to vlc 1.1.3), vlc no longer plays any videos (except mpeg2) as long as I have ffmpeg and libav.. from debian-multimedia.org installed. With all this packages removed and ffmpeg installed from the regular debian repositories, there is no problem, but I would like to have programs like dvdrip and k9copy installed as well.

Any ideas what to do?

Thanks in advance

Just pin the multimedia repository to a priority below 500, but higher than 100. This way, you will get all applications that are in the regular repositories from the regular repositories, and all applications that are not in there from the multimedia repository.
Have a look here and here for more information on pinning.

Thank you, but it seems that k9copy depends on the upgraded libs from debian-multimedia.org.