Thanks Jeremy. I was kind of moving in this direction, but the only thing that threw me was that TinyMCE editor and the default text box dimensions.
I deactivated the TinyMCE editor in plugin.php, but it defaulted to HTML entry rather than what I expected - something similar to the item entry fields. Is there a way to make a text entry box with no editor that will strip out HTML unless the "Use HTML" box is checked? That would be ideal.
Is there a way to resize the text entry area so that it can be made clear that a given field is for a URL, while the other is for the text?
Is it possible to modify the exhibit_builder_layout_form_item() function to achieve this? Possibly by creating a duplicate function with a new name and some modifications (fewer rows, different classes, etc.)?
In an ideal world, exhibit items would be added in a manner similar to WordPress media, with a choice to add from the whole Library or from a URL, but I'm sure that is not a realistic near-term goal.
To answer the question of why (a good one), we are trying to address some issues that arise from our student and teacher users. They don't always make great judgments about what kind of materials belong in a digital archive, and often will add things for use in their exhibit which are restricted by copyright, are not related to the site theme (Cleveland history), or are just completely ridiculous (one person added MS clip art). We still want to give them some freedom in constructing their exhibits, but don't want them adding unnecessary clutter. Thus, embeddable media templates seemed like a good option. they do what they want in their exhibit space without compromising/burdening the site owners.
Aside from this and the Contributor issue (addressed in the next release), the only other feature I would like to see in Exhibit Builder(and will soon be amateurishly pursuing) is a template that is well suited for audio display. Right now, it's kind of buggy.
But I am generally pleased with the plug-in. It does what it needs to do.
Thanks again for the thorough and thoughtful reply. -- Erin