For 12k a month just the DDoS protection would be worth it for a site of that nature and size but they also get CDN access with full control over the caching, and a web application firewall.
The way I see it the casino was trying to plate share at a buffet and got caught so now they are complaining about having to pay the correct amount.
You will get leagues better picture quality using a camlink/capture card and a camera with clean HDMI out. A gopro is a good budget option but a used DLSR or mirrorless camera is going to be the best. Some DSLR and mirrorless cameras support video out over usb so you don’t even need a capture card. Here’s a guide on getting it to work on Linux with a camera capability list inside the guide. If you do want to go the capture card route I hear elgato’s camlink works in Linux.