yuvplay: 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/yuvplay - from package: mjpegtools

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

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