yuvscaler: 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/yuvscaler - from package: mjpegtools

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

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