What exactly is the cam specs?
Specs on the engine, for a quick view here.
Parts, intake manifold, carb spacer, carb size, jetting , plug gap, what distributor, (standard HEI module, new, used, modules do not always just work or do not work, they can still work but give lousy spark, I know this first hand), coil, plug wires, ohms on plug wires,(even new plug wires can be bad, same goes for plugs.
I had a new set of Champion plugs & would miss every once in a while & took the longest time to figure out what the miss was coming from, found the ceramic porcelain collar was sliding down & covering up the spark plug gap.
The video seems to be like a not completely flat camshaft but a wearing camshaft, popping back through the carb.
Ignition problems @ higher RPM, not burning the fuel causing the fuel to back fire through the carb.
How much fuel pressure are you running, stock pump?
What is the A/F ratio showing when the miss happens?
MBHD