There is not a built in method to capture from a web cam directly into a container field. I created my own method to scan into a container with a scanner, which you might can adapt the method to work with your web cam. Steps I took : My scanner software allow me to save my image with a set name and path. I created a button to start an on timer script step to check if the file exist (I use the free BaseElements plug to check if file exist) then I have an open url script step to open my scanner software. The timer script uses the insert script step to insert the image into the container and then stops the timer script.
It's a bit weird that Go (for free) can do it but a paid-for FM package can not, isn't it?
Anyways, I don't know of a direct method without using plugins either.
Maybe, you've developed your own work-around already. But if not then an alternative to schamblee's solution could be the following. You capture the filename of the image coming from the camera and insert it in a text field in the table where you have the container field. You save the file in a folder and import it from there in the container field by hand or via a script (timered or otherwise). Use the filename at import to sync the image into the right record. You can do this file by file, but it's obviously more convenient to do it batch-wise.
It may take hand-work to enter the image file-name into the text field, but perhaps you may be able to capture it through additional programming outside of filemaker. I'm not experienced with FM on windows machines, so I can not help you on this point.
My guess would be that all iPad and iPhones use the same method for capturing pictures on them where as a MAC and PC don't use a standard method. MAC is different from a PC and then all the different PCs uses a different method / software to capture the image, which would make it more difficult for FM to program. Going back to scanners, most use twain drivers, but not all scanners use twain drivers, so it is more difficult to program for all the different methods / drivers used.