Hello,
Sorry to hear you are having trouble.
In any case, if the primary computer was KVM to the computer and the color showed like weird boxes in the image and wasn't responding to input etc, what would be pointing to? GPU on secondary?
This part:
'and wasn't responding to input'
Is likely a firewall issue, not a rendering one. Please see:
https://forums.stardock.com/486104/multiplicity-support-faq#movemousesecondary
As for the video, we have not seen anything like that before. If you have immediate plans to replace the GPU (it sounded like you may), I would be interested in those results. It may also be prudent to run a DXDiag on the laptop to see if any errors are found.