If you click on Title page->Scene you can see that the layer on it isn't the global layer like the layer on Page 1 and so on, so what you put there should only show up on Title page.
I make video object and I put Wait with option 'Wait forever' so even if the video stop playing it wouldn't move to the other Chapter.

I put my video objet on the bottom so it will become the background as requested.
And this is how it would looks like when you play the vn.

I have try and the video will playing just fine even if you click one of the button on Title page.

On the picture above I click Continue button and it open the Load Screen but after I click Exit [X] to back on Title page the video still playing just fine.
Hope this help
