I see multiple possible interpretations of your requirements...
1. First suggestion:
Instead of using taxonomy, my first suggestion is to create nested blogs. Because items are below each type of resource, they can easily be collected using '@self.children' by the child blogs videos, books and podcasts. The hierarchy keeps everything nicely organised.
A disadvantage of this structure is that a blog item can only belong to a single resource type. If items can belong to multiple resources, collections based on taxonomies could be used.
Folder structure:
/pages/
06.resources/
01.videos/
01.camera/
item.md
02.shooting/
item.md
03.editing
item.md
...
blog.md
02.books/
03.podcasts/
blog.md
07....
With blog.md files containing:
content:
items: '@self.children'
Note:
You will notice that the menu 'Resources; has nested submenus. If you don't want nested submenus, you can add 'visible: false' to the frontmatter of page 'camera' etc.
2. Second suggestion:
If you don't want to refer to pages stored (only) below videos/books/podcast but instead want to refer to any page containing a taxonomy field, you can use the following frontmatter in pages video/books/podcasts:
content:
items:
'@taxonomy.mytaxonomy': videos # or books, podcasts
Where 'mytaxonomy' is one of 'category', 'tags' or any other type (e.g. 'resources') added in 'site.yaml'. The collection will contain tagged pages from inside and outside the video folder.
3. Or a combination of 1. and 2.
content:
items:
- '@self.children'
- '@taxonomy.mytaxonomy': videos # or books, podcasts