After creating a script in OpenFunscripter and exporting it, why does OpenFunscripter ask me to replace the video assets when I open the video and script ? 
I don’t save .ofsp files personally.
My guess is that the file path saved in the project file is wrong or corrupted (incompatible character(s) in a folder name maybe?)
That just happens sometimes, usually due to moving the video/script files around. Just resave the ofsp or delete the old one. The only information that is really stored in ofsp is metadata unless you are using plugins.
John’s method can solve the problem of replacing resources
Doesn’t the automatic saving of OFS generate a .OFSP file? (I’m not quite sure about this)
You can just export and not save. Does effectively the same thing without the .ofsp file