DiscIO depends on some IOS functions and other functions, which are in Core and not Common. This results in link errors if using DiscIO on its own (which is why DolphinTool had a listed dependency on videocommon; videocommon has a dependency on core so adding that made things build).
Videocommon also depends on core, which resulted in linking errors (though I'm not sure why). Ideally, dolphintool woudln't depend on videocommon... but some stuff in core does.
