dh_gstscancodecs: 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/dh_gstscancodecs - from package: libgstreamer0.10-dev
/usr/bin/dh_gstscancodecs - from package: libgstreamer1.0-dev

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

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