Both Parallels and VMware Fusion use "virtual" graphics cards and
as such do not have the "protected" video path that is required
for Blu-Ray playback. For the most part, only HDMI interfaces
support this requirement. So, even if some how Parallels had
a video "feedthrough" feature, it would still only work if your
graphics card had the "protected" video path. This would also
apply using Bootcamp and running Windows natively.
So, if your computers video card does not have the protected
video path, there is no way you can playback Blu-Rays directly.
However, there are workarounds which I will not discuss because of
legality issues. Google it.