A short tutorial showing how to obscure a face with the Mosaic Effect in Premiere Pro. This works in every version of Premiere from CS3 to todays version. *BTW If you want to obscure more then one face, just duplicate the clip in track two by Alt + Dragging it into track 3, delete the old keyframes by clicking the stopwatch for 'Center' and drag the circle onto another person's face. Click the stopwatch for Center again and animate as I showed you. You can repeat this process as many times as you want using one video track with the circle effect for each person you need to blur out. You can also use a Garbage Matte instead of the Circle effect if you need to censor bigger areas or oddly shaped areas and with the newer versions of Premiere Pro you can automatically track the subject which is lots easier.
Sorry the video is a bit poor in quality, my screen catching software was set to SD by accident.