@Pyga You will need to create a Mix Minus. You can do this via the Aux 1/2/3 audio channels. Here's an example:
To get the remote speaker feed to your Tricaster, run Scan Converter on your non-Talkshow Skype PC. Make sure the correct audio source is selected in Scan Converter as well.
On your Tricaster, select this non-Talkshow Skype PC as an NDI source on Input 3
In the Audio settings of Input 3, turn off Aux 1 so Aux 1 doesn't get any audio from Input 3.
On your Output settings, change your Mix 2 settings to Program and Aux 1, so you're sending out an Aux feed that doesn't include Input 3 Audio with Program video.
On your non-Talkshow Skype PC, run Virtual Input and select Mix 2 as the source.
Run Skype settings and Select NDI as your video and audio Input.