Recommendations for a SQL Server 2014 Database Administrators Course
I would recommend signing up for a trial of PluralSight. They have a TON of content, including courses specifically aimed at 70-461 and 70-462. I have been a few of their courses and they are excellent: http://pluralsight.com/training/Courses#sql-server

Also, you may want to check out the MCM Readiness videos on Microsoft's site. They are a little out of date, but for things like index internals it won't matter a whole lot: http://technet.microsoft.com/en-us/sqlserver/ff977043.aspx