Identifying the source of a video recording created by a camera or smartphone has been a common and challenging task in media forensics for many years. We present an approach for source identification on the very common MP4 file format. In extension to related works, we propose to consider the suitability of attribute field values and their respective order in the atom/box tree in a specific manner. The significance of a field attribute and its particular value for source identification will be reflected by means of up and down weighting during the training and the matching process. Experimental result indicate that our approach allows distinguishing major brands. Even device identification is possible for a subset of our training data.