Next you'll need to extend your timeline. I have three videos, so I need to add on three frames, because I'm going to have one "page" to display each video. So for my background/design container, I dragged my last static frame out by three to give me a total of seven frames. Then I copied my navigation key frames on their layer to paste those frames into three more frames. Next, on a new layer that I set just for the videos, I added blank keyframes on frames 5, 6, and 7. I don't want to overlap my other frames; frame 1 is my home page, frame 2 my portfolio/thumbnail gallery, frame 3 my video thumbnail page, and frame 4 my resume page. If I put my video display pages on any of those frames but just on a new layer, they would display on top of that page content, and that could get a little messy.
Before we move on any further, go ahead and make symbols out of each one of the thumbnail previews. Make them buttons.