So fortitude no longer helps soak aggravated damage?
Ok so first on this...
"I did not ask how the stream was being done, I was asking about the rules because at times it seemed Jason was getting them wrong? "
"And I do think he did Obfuscate wrong unless 5th ed changed it..."
just like at many tables, GMs are free to run rules and interactions during streams as they see fit without being "wrong". many of the more popular streams make rulings, use house rules and a wide variety of options that may not be strictly RAW.
That is why i mentioned the bit about questioning how the stream was being run - as that stream like most VtM games i have seen played worry a lot more about scene than hard core RAW adherence.
I would myself be extremely hesitant to describe someone else as doing "it wrong" unless i had the rules and some experience with them.
But, as for your ongoing series of questions - in 5th the various disciplines give choices, not locked in powers per dot - and so fortitude may help with damage or may not.
Additionally there are quite a bit of differences between disciplines under normal use vs humans and cases where they interact with vampires and their interaction with other powers - far too numerous to expose here in any adequate detail.
The difference in blood potency are handled differently in 5th but many of the same kind of effects and results are there - just by different mechanics - again too numerous to go into detail.