Well not for DVDPlayer items, since DVDPlayer now set READ_NO_CACHE in case we disable buffering. Basically we have 2 options:
1) Have buffermode apply for everything that passes CFile::Open. This way you can also disable buffering for PAPlayer and all (other) internet files. In that case buffer-all means buffer everything that's from the internet AND/OR a video. I'm not sure whether this is desirable.
2) Have buffermode apply only for DVDPlayer like how it is now. In that case PAPlayer caching etc. is never touched.

As a side note: I do wonder whether renaming buffermode to cachemode isn't more appropriate and in case 2 perhaps even move it from <network> to <video> is as.xml just for consistency...