Perspective, Top, Front and Side are reserved keywords for the camera. You should NOT use these names as bookmarks. I've run into this situation before. Can't recall how I resolved it - I might've just created a new scene.
So when I try to change camera to Top the scene goes somewhere else and doesn't work. It doesn't matter what Bookmarks I export, there is always "Top" which destroys the video, even though I never chose "Top" as a bookmark
And one more thing, every time I open web scene, first thing I do is to change the left mouse button to rotate
You must have created a bookmarked called 'Top' before because I've ran into this exact issue. Once that bookmark has been made, you will not be able to remove it and it will not show up in the list. Try creating an entirely new scene from scratch, re-import all the layers and reset all the bookmarks.
Not a very practical solution, I know - had to learn it the hard way.