You cay 'certain', so you do not have a problem with all flv files ?
I see from a
post in the vlc forums they use
libavformat52 and
libavcodec51
The newest versions of these for Debian Lenny are in the Debian-Multimedia repository, do you have that repository enabled ? (I'm thinking you already do)
Code:
user@it-lenny:~$ apt-cache policy libavcodec51
libavcodec51:
Installed: 3:20080706-0.3
Candidate: 3:20080706-0.3
Version table:
*** 3:20080706-0.3 0
500 http://www.debian-multimedia.org lenny/main Packages
100 /var/lib/dpkg/status
0.svn20080206-17 0
500 http://ftp.uwsg.indiana.edu lenny/main Packages
user@it-lenny:~$ apt-cache policy libavformat52
libavformat52:
Installed: 3:20080706-0.3
Candidate: 3:20080706-0.3
Version table:
*** 3:20080706-0.3 0
500 http://www.debian-multimedia.org lenny/main Packages
100 /var/lib/dpkg/status
0.svn20080206-17 0
500 http://ftp.uwsg.indiana.edu lenny/main Packages
If that's not it, then it could just be however the originator of the file encoded it..
or as suggested in the thread I linked.. Try those libraries from experimental..