What version of FileMaker are you using? version 12?
insert Quicktime only inserts file references into the container field in the first place.
What you do is set up a related table of records with a container field in this table. Each related record's container field stores the reference to one document.
You can then set up your container field in the portal as a button such that clicking it either copies the container field contents to the large format container field or it copies the contents of a serial number ID field in this table to a global field used in a relationship to display the large format container field.
Either way, a mouse click on the container field in the portal then causes the document to appear in your larger container field.