For anyone that wants actually seamless switching of video and data, look to professional AV switchers and KVM. This Lindy 5x2 HDMI + USB KVM is the business [1]. I use one because I constantly switch between Mac and Linux while working on the same project and the couple of seconds of black really gets tedious pretty quickly.

https://www.lindy.eu/5-Port-Seamless-Multiview-KVM-Switch.ht...