Looks like you have your video layers around the wrong way.

Remember, they are layered in numerical order with layer 2 being over layer 1.

You have your main video on layer 2 and your titles (with transparency) in payer 1. Swap them over.

Have main video in layer 1 and then your titles in layer 2. The alpha channel (transparent bits) of your titles will then allow layer 2 to show through.

Let us know how it goes.