Generate B-roll you can't shoot with Runway
When the camera couldn't capture it or you don't have a crew, text-to-video fills the gap without stock-footage cliches.
B-roll is the easiest thing to fake badly with stock libraries. Runway lets you describe the exact shot you need, which beats hunting for 'office typing' for the tenth time.
Write the shot like a director would: 'slow tracking shot past a row of servers, soft blue light, no people.' The more camera direction you give, the less generic the result.
Keep clips short. Generated video drifts over time, so a four-second insert holds up better than a twenty-second take that morphs midway.
Use it to cover cuts in real footage, not to replace your main shots. A talking-head video with two well-placed generated inserts looks intentional; one made entirely of AI clips looks like an ad for AI.
Color-match the generated clip to your footage before publishing. Runway's tones can sit slightly off, and a quick grade hides the seam.