iOS file sharing - Videos

Hi, some iOS apps have the ability to do "file sharing" with iTunes, I need my app to be able to play videos that have been placed into the file sharer in iTunes, but I'm not sure how to do this, or if it's possible? To play videos with unity, the video needs to be placed into StreamingAssets, but I understand that StreamingAssets is read only?

I found this thread on how to allow file sharing and write to it, but how would I play a video from it? The videos placed in will be of a certain name, so I don't need any type of script that can tell me whats in there, and bring back names and stuff, so long as I can do 'play video /video1.mp4 for example.

I'm developing on Unity Pro.

Thank you in advance! :)