I think that is what it does. At least in this video it looks like the branch stopping the prop, only stopped the one prop and the others carried on. Although I didn't think it would spin as much as it does (kinda like a helicopter with the tail rotor damaged).
On my second flight (where I was trying to get the camera in record) I also hit a branch.. Both blades on one propeller snapped off. H landed quit normally on 5. No spinning like in picture. Put new prop on , no trouble ever since
I confirmed with Yuneec Tech Support. They said it should not spin. However, they said you should land it when it goes into 5 motor mode as soon as possible as it is not good to continue to fly it in 5 motor mode.