You can now filter Articles and Videos by Training Category in the mobile apps. The filter appears at the top above the search field.

Another enhancement is if you have categorized article or video links setup as custom pages then will show in the mobile app menu and open up inside the app natively rather than pop up as a browser window as they did previously.

More info on how to create custom menu items to filtered content see the help article http://support.trainingtilt.com/creating-and-editing-content/adding-categorized-custom-menu-items