The Level1Techs KVM Switch [video]
youtube.com
youtube.com
The KVM switches can be purchased here: https://www.store.level1techs.com/products/hardware
I've submitted the Linus Tech Tips video because it is a better overview and it discusses the problems in the specs. The following videos from the Level1Techs are a little older, less comprehensive, and are more incremental ("here's an update to our KVM!") in nature.
Sigh.