It’s a basic knowledge that goes a long way. That beautiful blue flower you see in the garden in real life is going to look very, very different when it is rendered in CMYK on a t-shirt. There are literally thousands of apps that assist in mitigating this difference (or manipulating it all together).
Try this: make a copy of your page and eliminate all design features: video, formatting, shiny things and all. Does the remaining written text compel you or anyone to buy what you’re selling? Does it explain what the thing is? What it does? What is your unique proposition? Clear? OK, NOW add things that only reinforce that core message.