How to place the flash? For example, the sum of the distances from the subject. Put it on the left and right, or before and after or something.

Can you explain your question more clearly? What are you filming? Do you have any requirements for movies? I think you should shoot indoors. I can't guess anything else and I can't help you.

It is not enough to take a photo with two lights: a main light and an auxiliary light (if only one main light has an angle, there will be shadows on the face, and if there is no angle, it will be dull and lifeless, and the background needs at least one light, otherwise the background will be dim) and there will be people in the background. Therefore, at least three lamps are needed (not necessarily flash lamps, but other lamps such as photographic lamps and high-brightness projection lamps, just pay attention to the matching of color temperature and illumination), and four or five lamps are better.

Three Lamps District: main light, auxiliary light and background light; The background light is placed behind people to illuminate the background cloth.

Four lights-a main light, an auxiliary light, a background light and a ceiling light-shine from the back, upper side and lower side of the person, making the head more stereoscopic;

Five lights can add a footlight on the basis of four lights, which shines obliquely above the front ground of people, making people's image more three-dimensional and full.