First Build, More Problems :)

[UnleRIco]

My new quad is not working properly. It has a vibration at low RPM and also the motors quit when I throttle down at all. Specifically I only throttle down the smallest amount, but the motors stop completely. I am attaching a video link. If the quad has a rough landing, I have to disarm and rearm it. Is that normal? I have arming set to a switch not the throttle, and I know that I am not accidentally throttling down all the way. I am still quite new to flying, crashed into the couch at the end of the video.

https://photos.app.goo.gl/SpsKpPJcw6WvxUx18

Thanks for any help!