Having purchased the Micro 2+ it appears that the only supported file systems are FAT, FAT32 and NTFS (except for memory cards that have to be FAT or FAT32), so it looks unlikely for external disc drive support.
Anyway I tried an external LG Disc Writer (Model: GP08 Lite) and it wasn't recognised, so I tried an external Blu-ray writer also LG but the result was the same. So either external drives aren't supported or in the very least the ones I have (which is a bummer!).
N.B. As it turned out the FLV videos on the discs don't work on the player anyway!, despite it's reputation for a wide range of supported file formats.