lav2avi: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/lav2avi - from package: mjpegtools

You may install the required package with command apt-get install {package}

Error in other languages:
lav2avi: bevel nie gevind nie
lav2avi: comandă negăsită
lav2avi: comando não encontrado
lav2avi: commande introuvable
lav2avi: command not found
lav2avi: käsku ei ole
lav2avi: không tìm thấy lệnh
lav2avi: komanda nerasta
lav2avi: Kommando nicht gefunden.
lav2avi: kommandot finns inte
lav2avi: komut yok
lav2avi: nie znaleziono polecenia
lav2avi: níor aimsíodh an t-ordú
lav2avi: no se encontró la orden
lav2avi: no s'ha trobat l'ordre
lav2avi: opdracht niet gevonden
lav2avi: parancs nem található
lav2avi: perintah tidak ditemukan
lav2avi: príkaz nenájdený
lav2avi: příkaz nenalezen
lav2avi: команда не найдена
lav2avi: командата не е открита
lav2avi: 命令找不到
lav2avi: コマンドが見つかりません