SQL server Virtual account and folder permissions
As long as you change the service account being used by using the SQL Configuration Manager, then it will configure all the necessary permissions for the new service account. 

https://msdn.microsoft.com/en-us/library/ms143504%28SQL.110%29.aspx#Serv_SID

Note that the mechanism that happens under the hood to grant these permissions has changed with the different versions of SQL, according to this discussion:
https://social.msdn.microsoft.com/Forums/sqlserver/en-US/9e6bb2de-8fd0-45de-ab02-d59bbe05f72e/servicedatabase-accounts-nt-servicemssqlserver-nt-servicesqlserveragent-what-are-they-for?forum=sqlsecurity