flv.sh: 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/share/mediathekview/bin/flv.sh - from package: mediathekview

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

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