Many companies build their own solutions to work with videos. For instance, encoding, decoding, cutting, making previews and so on. For a company which goal isn't providing such functionality, it's resource consuming to make its own solutions to work with video.
The idea is to provide video transformations functionality as API in a cloud. Thus, I can easily, for example, cut a video file, then reduce its size in one or two API calls instead of spending a huge amount of time implementing this myself.
Users can pay for an API call. Or tiers for a specific amount of calls per day, week, or month.