Smoke
The 1st trail is at full turbulence and you can see the smoke shoot the ssr /straight side and follow the wall to the far side bowl. That's the path of the dykem in post 1.
Watch the valve close some into stable air and then see the smoke take a more uniform path around the stem down the ssr.
Keep in mind smoke is not fuel and doesn't wet the port like fuel would. There is probably a better test with rapid valve open shut .100 to .400 then .200-.500 but would need a constant mist of dykem for a 10 second type of run.