Daniel Larimar incorrectly
claims in that video that it is not reliable to validate transactions in parallel multithreaded. Nonsense.
Why nonsense, it depends on linearity of the system. For a linear system order doesn't matter, for a non-linear one it does.
PS: We assume that multithreaded execution can't ensure a specific order of events, which is pretty reasonable for current architectures without placing a lot of memory barriers which would degrade the performance significantly.