I'm running a fresh copy of Mediagoblin 0.7.0 with the image, audio, and video plugins enabled. I attempted to upload an OGG file, and it initially appeared to work, but then showed up in the "failed to process" section of the media processing panel with nothing filled in for reason or metadata. The odd thing is that if I navigate directly to the URL of the generated webm (mgoblin_media/media_entries/<number>/<file name>.medium.webm), I can play the file just fine, so I know that it's transcoding correctly.
The only error I get is this warning in celery.log:
/srv/www/mediagoblin/lib/python2.7/site-packages/SQLAlchemy-0.8.7-py2.7-linux-x86_64.egg/sqlalchemy/engine/default.py:459: SAWarning: Unicode type received non-unicode bind param value.
Since there's no stack trace, I don't know where the source of the warning is in mediagoblin's code, but this is all I have to go off of.