Identifying license plate number of a thief's car from a video
Averaging may not be the best option, due to motion compensation in video frames: one number (say $8$) may be extrapolated for another (say $3$) on a different JPEG block. It might be interesting to dig into the compressed video format, check motion vectors, but this requires a little bit of hacking. 

Some software which can help:


Amped FIVE (used by the local CSI here, I learned it directly from them), with a live demo
Focus Magic, with a review here.


Unfortunately, while your videos are pretty good, the problem sounds quite difficult. For alight side, I'd like to share the following picture, that tells about issues in image forensics: