Is your phone carrier branded? I have a T-Mobile version and mine works fine, both sharing directly from the Gallery or uploading from the YouTube app. Have you tried clearing YouTube's cache and signing out/back in? Another thing I noticed is that when I share on mine, the window you're showing also has a preview of the video where you can also trim the running time, which is missing in yours. I imagine that's why the arrow isn't active, as there's no video loaded to share.