yuvmedianfilter: 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/yuvmedianfilter - from package: mjpegtools

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

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