When filming a video, does the camera go in front or behind the light source?

This is something for you, as an artist, get to choose!

Lighting ahead of the camera will be more harsh, for lack of a better word, because it will be closer to the subject.

Lighting behind the camera will be more diffuse, so softer and not accentuate contrasts in the subject.

Professional photographers use both depending on the effect they want. I had a friend who was a well regarded fashion and advertising photographer who would “paint” long exposure pictures by stepping into a scene and shining a flashlight on certain areas!

Since digital photography gives you many chances, experiment and find what you like!

“In general” the camera will be positioned between the two, with the light source behind the camera – and probably more to the site, too, in order to add more depth to the shot. But for special effects, such as backlighting or silhouetting, the light source may be behind the subject.

Like @zenvelo says, if it’s your shot, then you get to say where, to achieve the effect that you want.

Consider also the different types of lighting: natural vs. artificial (and all of the different types of artificial lighting); bounce; fill, reflective; and all of the different directions that light can come from.

Since photography is all about light, it’s the most important element in the shot, aside from the subject.

Here is one example of how to set up a portrait with two-source lighting.

When I worked as a volunteer at the cable company, we set-up two lights over each subject. They were between the camera and subject at a 45 degree above and on either side of the person.

It doesn’t matter if the light source if in front or behind so long as the camera and photographer’s shadow doesn’t appear in the shot. To help blend the light, use white cardboard sheets or panels to reflect light where you want it. What @Tropical_Willie said is important, too.

If the camera is in front of the light source then be careful not to cast the photogrphers shadow on the subject

Use the examples that @Seek has. Reflectors work great. I like to take my pics indoors set up near a window which depending on the strength of the sun light can work as a main light source with supplemental use of reflectors. Sunlight has a lighter color than incandescent bulbs and I get good color results when I use that setup and I use a overhead/back light sometime to get a different look with my still shots. Also hanging a sheer white sheet in front of the bulb lights will also help to diffuse the light for a softer overall light effect.