testH265VideoToTransportStream: command not found

Have You tried accessing the binary with the full path?

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/testH265VideoToTransportStream - from package: livemedia-utils

You may install the required package with command apt-get install {package}
Error in other languages:
testH265VideoToTransportStream: bevel nie gevind nie
testH265VideoToTransportStream: comandă negăsită
testH265VideoToTransportStream: comando não encontrado
testH265VideoToTransportStream: commande introuvable
testH265VideoToTransportStream: command not found
testH265VideoToTransportStream: käsku ei ole
testH265VideoToTransportStream: không tìm thấy lệnh
testH265VideoToTransportStream: komanda nerasta
testH265VideoToTransportStream: Kommando nicht gefunden.
testH265VideoToTransportStream: kommandot finns inte
testH265VideoToTransportStream: komut yok
testH265VideoToTransportStream: nie znaleziono polecenia
testH265VideoToTransportStream: níor aimsíodh an t-ordú
testH265VideoToTransportStream: no se encontró la orden
testH265VideoToTransportStream: no s'ha trobat l'ordre
testH265VideoToTransportStream: opdracht niet gevonden
testH265VideoToTransportStream: parancs nem található
testH265VideoToTransportStream: perintah tidak ditemukan
testH265VideoToTransportStream: príkaz nenájdený
testH265VideoToTransportStream: příkaz nenalezen
testH265VideoToTransportStream: команда не найдена
testH265VideoToTransportStream: командата не е открита
testH265VideoToTransportStream: 命令找不到
testH265VideoToTransportStream: コマンドが見つかりません