Cloud storage keeps media on infrastructure someone else manages, rather than on a server in your building. For a signage or video operation that mostly means the asset library: source video, images and rendered output.
It removes capacity planning, which matters more than it sounds. Video libraries grow without anyone deciding to grow them, and the alternative is a periodic scramble for disk that always arrives at the worst moment.
The caveat is that storage has three costs and vendors quote one. Storing is cheap; retrieving is not. Egress fees on a large video library re-published across a fleet can exceed the storage line by a wide margin, and archive tiers that look cheap per terabyte charge substantially to read anything back.
The second question is residency, and it is a legal one. Any asset containing personal data (a personalised video, a customer's uploaded image) falls under KVKK and GDPR rules about where data may sit and who may access it. "In the cloud" is not an answer; the region is.
Finally, ask how you would leave. A library you cannot export at reasonable cost is a commercial lock-in dressed as an infrastructure decision.