[junto]

Out of interest it works using Bittorrent right?

In Germany you won't have problems downloading movies, but uploading them gets you quickly a nasty letter and further abuses escalates to prosecution.

Since Popcorntime is using Bittoerrent, does it just download, or does it upload too?

[mpeg]

Both, like any Bittorrent client. The difference is it uses a library which prioritises certain file chunks so that you can watch it as you download (stream it).