Just something to add (not trying to be a downer) that even if that a beer is bottle conditioned, it may not be a brewery's primary yeast. If I recall, there are many breweries which filter and then bottle condition with a secondary yeast to protect proprietary yeast strains. I think there is a list of beers on the site which details successful yeast harvest and talks about that. If DFH is pretty guarded on their yeast, I think what you might have, if you do, is a secondary yeast. Good luck though.