Hello Robin,
it's still early days but things have indeed changed since that video. I need to get a bit technical here, so my apologies if this doesn't mean much to you - I know there are others who are very much into the technicalities of this topic.
That pre-AU3 multiport workaround used two discrete MIDI messages sent from Logic Environment to specify port number and channel number for each and every MIDI event sent from Logic's sequencer to VEP. It's a clever and creditable workaround by VSL and seems to work very well most of the time. However, I'm not convinced those two MIDI messages will stay together under all circumstances while being passed through Logic and onward via operating system core services - perhaps via an Ethernet LAN - to the appropriate VEP server instance. It's like trying to send a letter through the mail using two envelopes, each with a different part of the address written on it. Hence I suspect (though I can't say for sure) it may sometimes be possible for the port number message to be associated with a different (i.e. wrong) MIDI channel message by the time they reach VEP's routing - which can't be blamed for the confusion.
Since LPX 10.4.4 we now have Apple AU3 which, I assume, administers each MIDI event's data content and port and channel assignments within an indivisible packet or some sort of data frame which ensures port number and channel number always stay together with the associated MIDI event data. Thus it is to be expected that AU3 will ensure more robust and dependable multiport communication between Logic and each VEP instance.
As for how LPX 10.4.5 works with VEP AU3, I'm still working through it but from what I've seen and tried thus far, I haven't yet found a slick way to set up multiple ports for VEP7 AU3. But at least now each instrument strip in Logic can be expanded to provide up to 25 separate stereo pairs of audio from the VEP instance.
LPX 10.4.5 includes hundreds of fixes (though lord knows how much additional stuff they've broken as a result); see Apple's complete release notes here:
https://support.apple.com/en-us/HT203718