I'm impressed with this recent seminar covering aspects of PD and various treatments. It is targeted at a PWP audience so it's quite understandable (and even entertaining). It is quite long (1 hr 7 mins), with the second half mainly focused on the pig cell therapy from Living Cell Technologies (LCT).
youtube.com/watch?v=BRpvmLj...
(hat tip to soccertese at NeuroTalk for the link)