It is the same, just the UI looks a bit different, and it is a bit easier to deal with. With your slide selected, in the tool bar at top right, click "Animate". Then, with an element inside of the slide selected, just like before, select Build In, Action, or Build Out. For a transition to the next slide, make sure the slide itself is selected in the left hand column, and the Inspector changes to the slide transition mode. Set "Start Transition" to Automatically, just like before. Then set the time to be how ever long it takes the video to play. Not much has changed, only the interface.
If the Inspector is not already opened on the right hand side of the app window, go to the View menu, and make a selection in the Inspector sub-menu.