The box that comes up is labled Initializing Library, and once started there is no cancel button if you don't feel like waiting for the completion.
I was doing a TV.Adobe.com beginners tutorial about using items from different Catagories in the same Encore document so I imagine this is something that will be commonly done.
The answer to your question is no.
That said, and I don't want to risk my install at the moment to test it, I think you could go to the library directory, create a new folder (category) called "All Templates," copy all the individual files from all the categories into this one, and then select that category - thereafter that category should load.
Stop recording, load all the templates and go on with the recording, that is what i would do.
But explain it takes time to load them all.
I don't think he was recording the tutorial, he was watching it. And because the tutor is pulling assets from multiple categories of the library, Cris argues that this will be commonly done. I think it will not be so commonly done, but I agree it is aggravating to wait for a new library to load.
Well in that case load the libary before starting the tutorial.
Mine load very fast, depends on the machine you are running on, i think.