If you want your experience to match the videos then you should use the version of rails used in the videos. If you use a newer version you might encounter some problems that the videos dont cover. So if you are ok with having to figure out some stuff on your own when something does not work because of the versions, then you can keep your newer version. If you dont want to deal with that then use the version in the videos

There are not a huge amount of breaking changes between Rails 4.0 and 4.1. Except for one section which is outlined as Rails 4.1 specific, things should work correctly.