lav2avi.sh: 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/lib/mjpegtools/bin/lav2avi.sh - from package: mjpegtools

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

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