The product basically captures all messages sent to the OutputDebugString Win32 API function that would not otherwise be caught be a process debug. It can capture outputs from DbgPrint and KdPrint at debug mode.
The current version is v4.77. It is free. The command to capture debug info on the target machine (local) is
Dbgview.exe /k /v /l log.txt.
log.txt is the output file.
The server (agent) mode command is
Dbgview.exe /a /t /k
and so the remote machine can connect the target machine to see the debug output. The help command is
See more at "DebugView v4.77".