First off, I'm not a web developer. I do online marketing for a very small company, but this project has fallen to me. We are having a series of web videos created next week, and once they're done I need to be able to display them on the company's homepage in a nice looking lightbox gallery.
Our website is a template site created and hosted by a company that provides that service to businesses in our industry. The CMS provides the option to create and edit html within a certain div section of the body of any of the site's pages, but only within the body.

I found a program online called Video LightBox (I downloaded the free version to try it out, if we end up using it we will purchase the business edition) where you can input the URL of any video and it will create a customizable gallery based on different template options it has. Once you've created the template, there are a couple ways to publish it. One involves publishing directly to the FTP server. I don't fully understand FTP servers, and I don't know if the various login info I would need for that is something I could get. The other two options are basically different ways for it to generate the html code. I was hoping to be able to just generate the html code and then copy and paste it into the CMS.

However, that's not working. When I generate the code as an html file and open it locally, it looks how I want it to (these are just random YouTube videos for testing purposes). But when I try pasting that code into the CMS and pushing it live to the site, it ends up extremely broken . I think the issue might be that the code Video LightBox gives me includes information that needs to be in the head of the html document, but in the CMS I only have access to the body. Here's a screenshot of the code that Video Lightbox ended up generating.

If that's the case, is there any way I can "cheat" the code so that browsers can read the head info even though it appears in the body? Or will I need to have the site vendor put that into the head? Or is there something else I'm missing entirely?

Any help or advice would be extremely appreciated. Thanks!