FWIW, the memory crash and perf hitches I experienced on the stream were all due to one tiny bug in the BP. Under Debug-> the variable “Saved Pressure Divisor” should have been marked as user editable. Since it was not, the BP thought the setting “Pressure Divisor” was changing every time the script ran, which meant it was creating hundreds or thousands of render targets when I scrubbed. Scrubbing should be relatively hitch free and memory safe after that fix.
I suggest who has the BP to make that variable editable. It gets set by the BP itself and is how it tracks if properties have changed and whether it needs to create new RTs or not. This came about because merging BPs to an older build by hand has to be done manually.