Next to the play arrow, there's a button with 3 little squares on it. Click that once or twice and it'll bring up thumbnails of all the movies. Click on the one you want to watch and it'll start. It may play the next one automatically, or you may have to click the little box to bring the thumbnails back up.
Now with the addition of more videos, they don't all come up when you open up the thumbnails. To get the other ones to come up, click the little arrow just to the right of the first row of thumbnails and you will see the others.