Hi guys.

How is it possible to achieve that sunlight (or just any kind of light) effect, so frequently seen in movies and music videos (it looks horizontally emphasized and spread off the light's centre)?

Cheers.

Are you talking about a horizontal flare? These are a characteristic of some anamorphic lenses, but people put a 2 star filter on to recreate this effect on normal spherical lenses. You could also creat the effect in post.

There's another effect in which sunlight is caught in the og from a smoke machine, which create shafts or beams of light around an object or person.