They weren't used by game, so I removed them from mod.SVN-11095 update removes many *.bik files from Assets\Art\Movies\wonders. Is it intentional? I don't want them to go!
A lot of *.bik files are just static pictures by the way.
They are in Github repository - that is stored outside of mod, just like source code is in github only.
They can be reused later.