You mean something like this: https://bitbucket.org/memahaxx/drc-cap
That is still very different from having drc-sim (which is a Gamepad simulator) and a real Gamepad connected at the same time and somehow shareing all of the traffic between them.
No I don't mean a sniffer.
You put one or more devices (pc, raspberry pi ...) between console and gamepad.
The console and the gamepad are not talking directly to each other.
The device in the middle is controling the dataflow.
You basically send every ethernet package witch is send to port 50120,50121 and 50123 directly to the gamepad or the console.
Packages on Port 50122 (input data) have to be recreated by the Linux or Windows system.
The pros of this approach is that you do not need a kernel patch, because the timestamps for the video signal are created on the gamepad or console (I don't know where exactly).
So you may implement this on a windows PC (EAPHost can do this maybe).
Another pro is that you can use the gamepad with this method in vWii mode.
Basically the device in the middle takes the input data and emulates a vWii compatible controler,
video and audio streaming already works in vWii mode thanks to Nintendo.
The cons of this approach is that the latency increases.