Tips for filming?

I would like to start recording NTW videos, like my battles and stuff, I always see these really brilliant cinematic films on youtube, can you give me any tips for filming particular types of battles? Like should I keep a zoomed out view of the entire battlefield, focus on a certain unit, etc?

Also if anyone can give hotkeys in game that make filming easier that would be great (removing HUD, etc)

F5 F6 and F7 should clear most of the things on screen such as the HUD. If you press 'insert' once a unit has been selected it will go into first person and 'delete' will make the camera follow a unit. Also if you press 'N' it activates intelligent zoom which looks pretty cool.