If I have to pick only one Android app:
MapFactor Navigator
I'd probably use HERE Maps, but my current old Android phone (Huawei U8800) doesn't have 1GB RAM that HERE navigator requires. MapFactor works pretty ok on it, and uses free OpenStreetMaps. I dislike Google Maps as it relies so much on internet connectivity, it has left me on the road without navigation many times. To heck with it.
Other than that, for video files either VLC or or MX Player. I haven't made up my mind yet which I like more, for now I use both.
Post edited December 17, 2014 by timppu