Is there way to do this?
I don’t know anything about programming, but if blender is calculating the motion vector by vertex i’m sure that there must be some way to put that information inside the vertex color channel.
If that is possible then exporting the mesh to another program will be complete because you will be able to use the motion blur inside the other program, or at least inside of the composite nodes with the vector blur, but with the footage rendered in some other application.
Cheers.