Respect

Check out the information provided by the accompanying image.  If a photographer is doing you a favor then don't take advantage of his free work.  Don't ask for everything like doing both stills and video and on top of that expect him to cover a multi-hour event from beginning to end.  Also if he spends time to sort and edit photos before emailing them to you have the courtesy to reply with a thank you.  Or does a Thank You cost you much more than free?  If you can't do that then stay the f*ck away from me.