Audio-Technica ATR6550 shotgun mic
I shoot a lot of videos on a wide range of topics. I've worked in the television industry for many years and know the basics of assembling a video, including how to point a camera and how to edit shots together to make things look seamless. Directing a shoot is a lot of fun, especially when I understand what's needed to get all the cutaways and b-roll shots to get a good-looking finished product. I'll tell the talent that I need them to do something seemingly capricious, knowing that it's needed to make an edit. I'll get a puzzled look, but the light goes on over their heads when they see the finished product.
I also learned long ago that it's easy to get decent video, but it's maddeningly hard to get decent audio. More than anything, it's the quality of the audio that separates a good video from a bad video -- bad videos occasionally have good images, but they unfailingly have poor audio.
The simplest technique to get good audio is to put the camera as close as possible to the talent. I frequently hold my camera no more than 16 inches from the talent during an interview. This gets good sound even on the camera's built-in microphones. I recently got a shotgun mic and love the extra reach it gives me for good sound.
If the talent is just too far away, I do have wireless mics, but I mostly use a handheld audio recorder to get good sound. Actually, I will use a variety of devices, only one of which is an audio recorder -- I frequently use a simple point-and-shoot video camera, held at waist height by the talent, to get good location sound. (It works pretty well, actually.) I also use a cell phone in the talent's pocket, as well as a wired lavalier mic with a l-o-n-g cord.
Whatever you need to do to get good sound, it's worth it. I find that if there's a choice, I will more often compromise the video to get good sound. One of the best compliments I get is when someone watches one of my videos and says, "That was pretty good. I understood everything that was said."