Is the camera able to differentiate between a barcode and a regular photo?
It looks like what is happening in the video is different than what you are describing. I think the store has predetermined merchandise data that is already in Filemaker. When the first of any new products arrive the barcode is scanned and then the user is taken to the record for that product. From there a photo of the product is added to the system so users will have a visual reference when using the solution.
Looks like inventory control for unique objects. I use this heavily with barcodes. I do this on record creation and generate a barcode from a field that has an auto enter serial number. I print the labels as each item is entered and not in mass and then assigned. I get your idea as printing from filemaker is horrible from Go and just a hassle in Pro.
If you have preprinted labels you wish to assign you can run a scan script on record creation and that becomes your control number. There is no real need to keep them in a table except to keep a record of what numbers were already used.
If you are not using preprinted labels I do not see the use of having a huge table full of values. You can generate a unique serial number for each new item when the record is created.
To rename the file it is not as easy as it sounds on the iPad. The iPad assigns a filename. There is no native way to rename that I am aware of. There are plugins for this but they do not run on the iPad. You may be able to run the plugin on the server side and PerformScriptOnServer, but I am not sure the plugins will work server side.
I am not sure you really need that functionality when the photo is taken but rather when the image is exported out of filemaker. This is easier to manage the renaming on export. This is what I do.
You will need a way to identify the instance. For me I have a maximum of 13 images for each item using 13 independent fields in an images table that are related to the record. There are other ways to do this as well. You can add images through a portal and not have the extra fields empty. Each way has a benefit or hinderance depending on how you look at it. For my case keeping the rename fast and solid was what I needed. I also know that most 95% of what I deal with uses 10-12 images all the time. The instances are static to the fields. There is a Layout with 13 containers on it. They are tapped individually to add the images to a particular field.
If you have some things with with 3 images and some things with 25 you may want to consider a portal and creating related records on the fly with some scripting to assign an instance number. Either way I suggest storing you image name data in a field and assign it at export as I believe that is the only way. Well you can start looking at robots and scheduled scripts or remote scripts, but that is more stuff to manage and it costs.
You could use a repeating field to identify the instance but it can get messy.
If you are using the InsertFromDevice script step you can force the iPad to know whether it is looking for a picture or a barcode. You can even tell it what format of barcode to look for if you have a few in close proximity.
Beware of QR Codes. When you initiate a scan in Filemaker Go for a QR code and the iThing is already pointed at the code when the script is run the app crashes. The only helpful advice from Filemaker is to point the camera away from the barcode and then start the scan and find the QR code. Only an issue with QR codes. Other barcode types do not have this problem. Filemaker does not seem to think it is a big deal as they have not fixed the problem in nearly a year but have had some updates.