Video Quality Decreasing when Project Published

I'm having to add videos to my project but can't have them streaming from a site, they have to be 'enbedded' into the project. When I create the videos the quality is great, but when I add them to the project and publish the quality decreases and I get fine lines.

Project size: 1180x885

Video size: 1090 x624

I read somewhere that if I untick 'scalable HTML content' when publishing that would improve the quality, but the improvement is not noticeable and the user then has to scroll up/down.

Any other ideas?