By using the Search field one can find bookmarks in Firefox. Is there any way how to locate the found item in the hierarchical bookmark folder structure?
The usual scenario where I need such capability is when I want to add a new bookmark to the existing ones at the appropriate location in the bookmark folders, or to check the other bookmarks contained in the same folder as the found one.
"Show parent folder" add-on, below, will do this; the 2nd add-on is helpful.
https://addons.mozilla.org/en-US/firefox/addon/show-parent-folder/
https://addons.mozilla.org/en-US/firefox/addon/go-parent-folder/
The hard-core method is to open the sqlite database places.sqlite (this is where bookmarks are stored) in your Firefox profile folder using e.g. sqlitebrowser.app.
Parenthetically: this longstanding and well-known functionality gap in Firefox search is inexplicable and insanely annoying.
For adding a bookmark in a particular location in the hierarchy:
https://addons.mozilla.org/en-us/firefox/addon/add-bookmark-here-2/
Edit:
An additional trick to enable search for both bookmarks and folders is to have Firefox automatically dump the entire set of bookmarks as file at each exit.
This can be done by going to about:config in the URL bar and setting the option browser.bookmarks.autoExportHTML to true.
The bookmarks file (by default, bookmarks.html in the profile folder) can be linked to with a shortcut, and then searched as a regular HTML page using full-text search.