mp4file: 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/mp4file - from package: mp4v2-utils

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

Error in other languages:
mp4file: bevel nie gevind nie
mp4file: comandă negăsită
mp4file: comando não encontrado
mp4file: commande introuvable
mp4file: command not found
mp4file: käsku ei ole
mp4file: không tìm thấy lệnh
mp4file: komanda nerasta
mp4file: Kommando nicht gefunden.
mp4file: kommandot finns inte
mp4file: komut yok
mp4file: nie znaleziono polecenia
mp4file: níor aimsíodh an t-ordú
mp4file: no se encontró la orden
mp4file: no s'ha trobat l'ordre
mp4file: opdracht niet gevonden
mp4file: parancs nem található
mp4file: perintah tidak ditemukan
mp4file: príkaz nenájdený
mp4file: příkaz nenalezen
mp4file: команда не найдена
mp4file: командата не е открита
mp4file: 命令找不到
mp4file: コマンドが見つかりません