mpgprobe: 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/mpgprobe - from package: dvdwizard

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

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