Actually works! Rated 4 out of 5 stars
Does everybody know that this extension makes an excellent workaround to Mozilla's incompatible-with-itself .json/html bookmark system?
If you try to import a .json file that you foolishly thought would be accepted by your new Firefox install, you'll know how badly Mozilla shot itself, and us, in the foot. [If you try, your present bookmarks will be replaced by the .json'ed bookmarks!!! Doh!]
Yes, there is a workaround, involving creation of a new profile [come on rover, just jump through these ten more hoops!!
You can save yourself most of that work by using JSONView to open the .json, then manually transfer URL's to firefox [open URL, Ctrl+D to install as new bookmark].
Thanks Ben, for saving me from Mozilla.