The pipe you all are referring to is called CSST (corrugated stainless steel tubing). There are a numbef of manufacturers of it. Wardflex,Gastite,and several others I can't think of at the moment. They all have their own proprietary fittings, and you have to be certified by the manufacturers of each product to buy and install it. You could use soft copper tubing and flare fitting to run the new line if the local code enforcement allows it.
You should also check to see if permits and inspections are required in your area.
The flex connectors that were referred to usually come in 1 foot to 6 foot lenghts and are only approved to use as appliance connectors after the valve that is required to be at the appliance.
These are some of the National Fuel Gas Code requirements, which should be followed in any installation.
Larry