1. A method of estimating global motion magnitude in digital video frames, the method comprising: identifying for each of a plurality of features in the digital video frames a best motion vector among a plurality of candidate motion vectors that most closely corresponds to the motion of the feature between a first frame and a second frame and a second best motion vector that second most closely corresponds to the motion of the feature between the first frame and the second frame; assigning a confidence level to each best vector based on a comparison of the best motion vector with a respective second best motion vector; calculating a magnitude of each best motion vector; determining an average motion magnitude based on the magnitude and confidence level of the best motion vectors; and estimating the global motion magnitude based on the magnitude and confidence level of each best motion vector having magnitudes within a window of magnitudes surrounding the average motion magnitude, wherein the best and second best motion vectors satisfy the following condition: 
 | m min 2 −m min |+|n min 2 −n min |>1 wherein m min , is the horizontal component of the best motion vector, n min is the vertical component of the best motion vector, m min2 is the horizontal component of the second best motion vector, and n min2 is the vertical component of the second best motion vector.