there is a book called "what makes you ill" by S. Mayes I know about this one because it is an Usborne book. (www.celestsbooks.com)
I got to thinking about it though and I found this website
http://www.librarything.com/tag/germs
it's a huge list of books on germs.
I didn't find any movies about it though. I wonder if your local librarian could help? they might have something.
I found a website that might be of interest
http://www.stopgerms.org/
okay looking around a bit more on some of the books (I love books so I got a bit carried away researching this lol) I did find one video...
https://store.latsa.com/product.php?productid=239&cat...
I'm not sure how good it is, but the book that is with it has lots of great tags and reviews.
I also saw a demonstration once with some glitter...the teacher put a little glitter on one kids hands and had them touch another kids hands etc. until you looked around and everyone had glitter, not just on hands but on noses, on the desks, the floor etc. just little specks of glitter everywhere to show how germs spread and spread and we don't even realize it.
anyway I hope some of this helps! lol. the company with the video has several books on germs as well. they look interesting.
good luck.