The picture in your first post is a direct acting valve.
I think that picture with the modified airgun does not use a direct acting valve. It uses the air pressure itself to open en close the valve.
Here is more information:
This is the used valve:
It will be hard to find something similar to that. And I still have my doubts if that is even possible with a direct acting valve. So you could use the same valve as in the tutorial. Other similar valves are bigger.