From what I can see, it looks like your model geometry might be miss-aligned. If you could upload the model that would be great. That way, I could take a closer look and try to confirm the cause.
I agree with @C13229 , the behavior in you video looks like points are not coplanar, causing faces to be triangulated. It is not possible to tell what size your model is, but it working at too small a size in SketchUp can aggravate this problem. And, as he says, the only way for us to say for sure is if you can upload your model.
I solved the problem before this post got verified, sorry for the trouble.
So what was the solution? It might help someone else.
I up-scaled the model and was able to fix the surface I then down-scaled the model.