mpeg2dec: command not found

Have You tried accessing the binary with the full path?

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/mpeg2dec - from package: mpeg2dec

You may install the required package with command apt-get install {package}
Error in other languages:
mpeg2dec: bevel nie gevind nie
mpeg2dec: comandă negăsită
mpeg2dec: comando não encontrado
mpeg2dec: commande introuvable
mpeg2dec: command not found
mpeg2dec: käsku ei ole
mpeg2dec: không tìm thấy lệnh
mpeg2dec: komanda nerasta
mpeg2dec: Kommando nicht gefunden.
mpeg2dec: kommandot finns inte
mpeg2dec: komut yok
mpeg2dec: nie znaleziono polecenia
mpeg2dec: níor aimsíodh an t-ordú
mpeg2dec: no se encontró la orden
mpeg2dec: no s'ha trobat l'ordre
mpeg2dec: opdracht niet gevonden
mpeg2dec: parancs nem található
mpeg2dec: perintah tidak ditemukan
mpeg2dec: príkaz nenájdený
mpeg2dec: příkaz nenalezen
mpeg2dec: команда не найдена
mpeg2dec: командата не е открита
mpeg2dec: 命令找不到
mpeg2dec: コマンドが見つかりません