Pro connects you to 2 extra ultrapeers, so there's the potential for better search results. Pro will let you download from 10 hosts (14 if you have a T3 connection).

How long does it take to download movies? That depends on your connection speed, how many hosts you're downloading from & their speed, size of the file you're downloading etc etc
If you want to know more about Pro vs basic, use the forum search to look through old threads. You'll find heaps of different opinions! If you've got a pretty slow connection, Pro's not going to make much difference at all, if any.