The muffler bodies are stainless steel, and not sleeves. I can check into chrome plating costs, but I think polished would give you the same result you're looking for... and it's stainless and not chrome.
Yes, the video is with the db-killers in. In my experience, the sound and performance is better with them in. I don't believe anyone would find them favorable with them out. They are quite healthy sounding in person with them in.