This was discovered because the video upload feature in Studio does not set created_by. On export, the created_by element for the asset contains the text None. On importing, an error is raised when the asset store tries to parse "None" as an int. A file that triggers the exception is attached.
On a more general note, we shouldn't be importing edit_info for assets, because it contains user information that is specific to a particular deployment. Rather, the edit_info should contain the information of the importing user. Given that, it seems like it would make more sense to not export the contents of edit_info.