Video Slide Layers and Triggers

Hello.

 

I need to set up slide layers (which have the text of that video) to show up at the correct intervals in my video. 

I want the students to be able to read the words as she is talking.

It seems there is a difference between the video playing time and the Storyline run time. The layers are off by a few secinds each time I work on this.

I have looked for other messages in the forum but can't seem to find the exact information I am looking for. 

Can someone please guide me?

Thank you,

Laura