Actually, I know this exists, I've seen it before on PPro. Simple plugin, lets you choose either mosaic, black rectangle or blur, applied on a specific portion of the frame you want to hide, "cops" style. There's motion tracking in this plugin as well.

Rings a bell for anyone? I've searched the net and can't seem to find it back.

It is really quite easy to do this without a plugin. Simply put a 2nd instance of the clip over the original and use a garbage matte to select the area to be distorted. Then either add a blur, or a mosaic, or mess with the levels to make it black or white. No plugin needed.

Are you thinking of "Witness Protection" in Boris Continuum Complete?

Yes I think that's it Graham thanks!

Steven, would that be any good for moving subjects (and cameras) though? I know I could animate by hand but I want something that pixel accurately moves with the subject, not an approximation. I know AE has motion tracking, but I don't think PPro does, and I do not own AE.

Take a look here for a tutorial on "Blurring or Highlighting a Moving Face (or Object)" in Premiere Pro:

http://www.wrigleyvideo.com/videotutorial/tutdes_ppro_blurface.htm

Thanks for the link John I'll have a look at it.

Pixel accurate could be a problem for any program unless you rotoscoped it. Faces change as people talk, or turn their head. On the other hand, you might be able to easily track it by being a little less stringent like in the tutorial.

I have used that feature many times with Premiere 6.5. Below is a link to a video concealing multiple individuals in a single shot as well as license plates, etc.. When the shot was wide I just did a band at head level to save time. It took about 2 hours to keyframe all of these masks. I have heard that high end software can track a pixel to cut down of tracking time. I have found that all of Premiere's blur filters just aren't blurred enough to hide features well enough. What is really strange is the more you increase the blur value, you can actually see through the blur more than with a lower value. I know about the mosaic filter but I don't like that one and really don't like black boxes. I finally tried doubling up or stacking the tracks with identical video clips and masking mattes increasing the blur value on the second pass by 3. This fixed the issue even with close ups. Even though the data rate is high and the video is clear in the demo below, the compression helps to further blur the masks which is great for the online version. However, when the native uncompressed video is viewed on a CRT monitor it is much sharper and the blurs aren't blurry enough. So I used the fix described above.

Blur Demo Video (http://www.jefcommunications.com/video/dvi/id.blur-demo.wmv) (13.4 MB)