When I select an album and "open containing folder", Foobar opens the folder that I need but when I select various albums the option is greyed out. So I suggest that Foobar opens, if two albums (folders) selected, the two correspondent folders at once not having to selct one and then the other one.
I suggest it because when I need to open two folders from different artists it is annoying not having this option that I found it would be a time saver.
You ask then for an old foobar's behavior, present I think before v 1.0 or 1.1.
Currently the only way to revive it is to install foo_run ( http://www.foobar2000.org/components/view/foo_run ). It has predefined function for opening directories and it opens several folders at once when marked files come from different ones. Usage is not convenient - at least of of box. You need to do a rightclick on your files on playlist and then to go to "Run service -> Open Directory". But you can make it bit easier by adding your own keyboard shortcut to this function...