You just don't have latest info, that's OK. Note, due to regulatory changes, modern spray "carb cleaners" no longer work. They don't have chlorinated compounds such as trichloroethylene, carbon-tetrachloride, or chlorobenzene, which does actual job of cutting polyvinyl bonds in dried petrol. Nowadays, spray "carb cleaner" is just weak carrier solvents that does nothing. I used to clean off inside of sprocket covers with carb-cleaner, and it would drip out as tar-like sludge goo. Now, it drips off clear-grey having dissolved nothing.
Well, that Youtube procedure is cursory 20-25℅ of the job. You'll want to do deeper more thorough cleaning. Kinda like difference between rinsing your mouth out with water versus actually brushing it. You'll want to trace flow of petrol from tank to carb-venturi and scrub clean entire path.
First stage is petcock. From original post, you have at least 2 problems. Leaky petcock and leaky float-valves. Both have to occur in order for petrol to drip from tank into engine. Bad petcock can also limit flow in addition to leaking, so let's test petcock flow. Pull fuel-hose from carb-inlet and aim into measuring cup. Aside from initial dribble, it should not flow any petrol!. Then apply vacuum to petcock and measure flow for 30-seconds. How much did you collect? Also note if you had to continually apply vacuum to maintain flow.
Now if petcock flows enough, you will probably need to do
complete restoration job on carbs. Many people in your situation have had to pull carbs 4-5x with doing ever deeper and more thorough cleaning. I recomemded you do complete restoration job. You've already pulled them once. As Dirty Harry said, "Do you feel lucky?" Do you really want to pull them another 3-4 times?