From what I can see, Amber is fine with her weight. First, for a long time, she wanted to be in the 400's and not the 500's. The fact that she is almost 500 pounds is not important to her as she counts a loss of a fraction of a pound a success. Further, from her point of view, WW allows her to eat about 5,000 calories a day and this way, she can still maintain her weight just under 500 pounds. She can eat what she wants and call it a success. It is a maintenance diet.
Her relationship with Jade is really non-existent; they are roommates. Jade stays in the master bedroom while Amber is in the second bedroom. Jade pays for a good portion of the rent and utilities. Since Jade works during the day and Amber is up till the morning, Amber has a pair of earphones so that she can listen to videos without disturbing Jade. Likewise, Jade does the same during the day. They are not eating together. The food haul in the video 2 days ago was all Amber's. I do not think that Jade pays for the food Amber eats and orders. So, they cook separate meals like Amber and any of her girlfriends did in the past.
As for the car, I do not think that Amber paid for it and I do not expect that Jade will drive Amber as Becky did. Jade has a need for a car especially if she wants to go to clubs or meet people or whatever. She is not likely a homebody and does not want to be cooped up with Amber all the time.
Jade has no interest to be on camera; she is not going to share her life with Amber as they have so little in common. When Jade has enough of Amber, the separation will be quick and glorious.