@Nikhil hey mate, many thanks for your valuable ideas.
What we want to do is make file management simple enough to all users. This is why we bring significant files to users by categories on GUI.
I believe poeple should not need spend time to browse folders/directories to find some files out, but need a quick portal to reach files they want.
Just image, while you need to find a picture or downloaded picture out, you do not need to care which folder it is in, what you need to do is just tap Pictures or Download button, and then you will not miss it.
Another question to "Exit", I will discuss with my dev team, to see if we could do something to improve it.
And the checkbox, what we want is just make “Select a file/folder" clear and simple. So, while users want to select something, they do not need to press for a while, since such operation is like some hidden thing.
About Buffering or cached medias on SMB server, I think it is kind of work to media player. But I will discuss with my dev team to see if we could do something and make it more friendly.
Many thanks for your good suggestions.