This extension for FTDNA's Family Trees and for 23andMe's "classic" Family Trees (i.e., 23andMe trees entered before their discontinuation in 2015) extracts information from a displayed tree and presents it as a list in Ahnentafel format. When available, ancestors to at least 7th great grandparents (8th cousin relationships) are displayed at 23andMe, and up to 15 generations are displayed at FTDNA. Clicking on an individual's entry will highlight their descendants and their ancestors based on the selected inheritance mode (autosomal, X chromosome, mitochondrial or Y chromosome). 

Step 1: Load a family tree (wait for the "loading" icon to stop spinning)
Step 2: Click on the DNArboretum icon located on the right hand side of the URL bar (see screenshot)
Step 3: Wait for the "loading" icon to stop spinning, this can take some time for complex trees
Step 4: The DNArboretum page will automatically open
Step 5: Select the Inheritance mode of interest (defaults to autosomal)
Step 6: Click and explore; search for names and places

For more information, 23andMe users please see this thread: https://www.23andme.com/you/community/thread/29714/

Version 2.0.0.2 circumvents a Chrome bug that prevented FTDNA trees from displaying consistently but requires the user to perform a redundant button push (for the technically minded, setTimeout() does not achieve the desired result). Not elegant, but it works again.

Version 2.0.0.3 fixes a bug that caused some ancestors to be omitted from FTDNA trees

Version 2.0.0.4 may address certain errors in trees with multiple spouses