Thats the idea of a symlink, its faster as it will retain the same format of the source file eg mkv, if you encode to a different format it will take longer and may fail, the best most compatible format to use with most devices is mp4, next is mkv those are the only 2 i use, you also need to create a category and a bouquet for your movies then you can place each movie in its correct category and bouquet, hope this helps.