Did anyone read the YT description by the guy who put it on YT? ... note the parts in bold. Think that engine has some factors that effected what they saw. IMO, not a good test of a cold start-up to determine time it takes for oil to get to the rockers.
"My 350 SBC with a wore out bottom end. This engine has an Edelbrock Performer cam and lifter set with Summit 1.6 ratio roller tip rockers. This was a cold start after sitting for about a year. I wanted to see how fast oil got up to the rockers since we have been having problems with my brothers Camaro. It took a while to get there. With good oil pressure in another SBC we were seeing 20 seconds for oil to get to the rockers, and much more flow when it did. That was with Lunati lifters. This engine makes almost no oil pressure at idle when warm. Check out some of my other videos for that engine to compare this to."