You can, as long you're not using it for publications. The usage on your own blog or Facebook account is allowed but the line is drawn at billboards, on TV or such (larger) channels. For those you must have an agreement.
You would have to justify it anyway and personal rights in Germany always trump the rights of others to create art, for example. You'll find many cases that are about surveillance cameras as well and even there's it's often in favor of the person not wanting to be on camera.
https://dejure.org/dienste/vernetzung/rechtsprechung?Text=VI...
http://lrbw.juris.de/cgi-bin/laender_rechtsprechung/document...