Clicking on the magnifying glass in the top right corner of the collections page will take to you the search page, which has an input box that will allow you to search across all your libraries at once.
The results will display: title, creator (author/director/etc…), library the item resides in, any ratings you have given the item, and an icon which indicates the type of item it is.
The top right tag icon will reveal a list of any tags that you have added to your items, which you can click on to search.
Tap on any of the items to view its details, or slide the item over to reveal the edit and delete options.