Nice idea for OSF, it seem a right place for .bag, they also got some API to connect to external application and they can even redirect the project main page to an external website : http://help.osf.io/m/addons/l/524148-connect-add-ons#External-links
Github is not the right place for storing large dataset, each repo are limited to 1GB : https://help.github.com/articles/working-with-large-files/