Yes. Watching the second video, you can see the second car's brake lights come on quite quickly, given the Tesla's actions were completely strange and unexpected. Less than a second from when the Tesla cuts in front and starts braking to the vehicle behind hitting the brakes. They're definitely not at fault. Some of the cars that piled in behind were a different matter though. Some were able to stop while others didn't. Those ones must have been following too close and/or not paying enough attention.
They didn't actually stop their car, though. And it really looks like they could have, had they braked a little bit harder. But that may be due to the unexpected nature of the Tesla coming to a full stop.
Yeah, it's possible they didn't fully slam on the brakes immediately. But you don't expect the car in front of you to do so for no reason either, so I still wouldn't consider the second car at fault.
