Yes it is a scam because it says that YOLO is ultralytics. That's the wrong point. There are hundreds of different YOLO implementations. Just search for some bookmarks or look in huggingface. Paperswithcode is dead now, hugging face built something similar.

DETR model have outperformed YOLO models for a while, but they have been much slower making them impractical for real time detection.

A small percent difference means nothing at all.

Your camera will be very different from the images the models have been trained on, so you'll have to do fine tuning. So the only thing that matters is this phase.

Plus, there are models that run device, on servers etc.