Google "scan barcode site:forums.filemaker.com" searches these forums.
The link you posted specifies FMGo version 1, you are using FMGo version 2, I assume.
Link #1 Scanning Barcodes with FileMaker Go for iPhone (skeletonkey)
Link #2 CNS Barcode is an iPhone/iPod Touch/iPad* app for scanning and generating barcodes $10
Link #5 Scanning Barcodes and More with FileMaker Go – Part 1
First, your iOS device will require some software and hardware. FileMaker Go is free, though you will need to develop your database using FileMaker Pro on the desktop. To read bar codes I have used two different apps. One, Pic2Shop, is free and performs its task fairly well, though it is limited to scanning one item at a time. CNS Barcode costs $9.99, but adds a variety of features such as multi-scanning, and also can create bar codes.