Read this:
https://www.servethehome.com/exploring-best-zfs-zil-slog-ssd-intel-optane-nand/

And chuck one of these in as SLOG (ZIL) and your synchronous writes should fly. I think vid editing is more this way than asynchronous (small files r/W). Maybe an OP can comment?

https://www.amazon.com/Intel-Optane-900P-280GB-XPoint/dp/B0772XB3MY