I have the Lionel UP wifi camera caboose. I think it is awesome. However, I was disappointed that Lionel did not make their camera app for the Apple TV (in my mind: phone = train control, tablet = layout control, tv = layout view). I started searching the app store for various apps that might work. I eventually found Streamie.
Was able to find my lionel camera and watch my layout on the big screen without any other devices needed. The app is free for one camera one device.
more impressive, when using the app I was having issues, so I tried reaching out to the developer. I had low expectations since I didn't pay for the app. He responded and worked with me to understand my camera. He asked me for links to buy his own train and camera caboose so he could test it out. He could not reproduce my issue. A few months go by and he finally figured out and has released a fix to my issue. What a great person, I spend $0 on his app so far and he spent $100's to make his app work for me. I do plan to upgrade to his pay for version that can handle more than one camera as I have lionel wifi camera car on order.
If you have an apple TV and lionel wifi camera car; this app is great and costs $0.