Ecopco; the video is certainly informative, but unfortunately (IMHO) it gives wrong advice for Berkshire owners.
First of all, by feeding an external low pressure source into the RV's low pressure side, the Berk's safety valve that is connected to the inside gas sensor will be compromised. If there was a gas leak, the gas sensor would shut off the RV's supply but not the external source.
Secondly, most people use propane tanks without regulators to connect to the Extend-a-Stay and do not have the problem depicted in the video.
Last of all, most Berk's at least from 2012 and up have a low pressure quick connect coupling on the patio side and don't have to run a mile of line from the driver's side for a barbecue. However, since most barbecue's require high pressure, the barbecue's regulator would have to be removed.