Yes. That's the choke. It's for starting the car. The process is to set it by pressing the gas pedal, take foot off the gas, and crank. Repeat until start without feathering the gas like was being done in one of your videos. All you do when you do that is flood it out. This is NOT like starting a modern car.
When you check for a burst of fuel, which gets sprayed at cold start from hitting the gas pedal and also setting the choke, it goes into the PRIMARY bore- the bore with the choke valve, red rectangle side in your pic.