In recent years, DSLR lenses have been designed with video in mind. That being said, you might run into issues when your lens re-focuses mid-scene, and you have to start over. Lenses can also be noisy when they’re shifting focus.
Autofocus is awesome for honing in on fast-moving subjects. But for everything else, turn off autofocus and manually focus your lens. This will prevent your lens from making any automatic adjustments while you’re rolling. It’ll also encourage you to experiment with focus techniques for a dramatic effect.