i have 2 admit i never tried it b4 or even used the mic that comes with it - hey , once my HU is working fine i don't mess with it much & thats all that matters .
I downloaded a new movie and put it on my 860mp. The only draw back is that it overwrites one of the movies that comes already installed on the head unit. I forget which one it over writes though.
The manual really does not touch the subject at all. I have written to the unit a couple of times and even though there is supposed to be some rhyme or reason to what you are doing it does not make any sense to me.
Most I can say about it is, no matter what you have the originals on Pioneer site so no matter what you can always put them back.
I put a couple of custom thinks on mine (por*no movies ha ha) which got old after a while and then just downloaded and reloaded all the originals from the Pioneer site. It's really kind of a joke anyway since everything is squished to the size of the display. There are a few site that I found (do a search for Pioneer LKA files) that have other ones but I could never get them to work with the Pioneer software.