If for example I have two video files, both of similar characteristics, file type, encoding, resolution, etc and starting at the same point but A goes on for 10 seconds while B goes on for 20. If A's file size is 10MB and B's is 20MB, if I read in e.g. the first 5MB from both will the major video encoding formats' binary sequences match for that 5MB?
E.G. MP4, AVI, MOV, WMV?