avplay: 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/avplay - from package: libav-tools

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

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