Expanding on this, the geniuses who created these formats (read major japanese and korean consumer electronics companies) didn't think about having a way to automatically identify them. As a result, the player goes through an ordered process of reading format A and if it gets error, goes to format B, and then C, etc. What of the executives at a major CE company told me one of the format reads can actually damage some types of writable formats! So it was a major headache to make a universal format. This, on top of myriads of patents around every format. Totally screwed up.
Anyway, as John says, a multiformat player may put priority on movie formats before CD so can take a while to read the CD and play it.
