Ok I created a new page as a test on my facebook. I could post video and pics on it this is how I did it.
Went onto facebook via Internet explorer in my phone.
Pressed the icon on the top right corner (where you see Favorites, Apps etc) scrolled down to my page I created.
Then just tapped the camera icon and my pictures and videos came up as options to add to the page.
Then posted as normal.
I tried the facebook app and I couldn't upload videos only photos. So in short use the Internet explorer version of facebook on your phone. Then you can do everything you need on there.