Space Saver is a new feature we're introducing that will better maintain the storage space of your account through downsizing the space of stacked versions as your projects grow. Each stacked version you have on a video currently requires a complete upload of the original video file. Wipster then creates two encodes on top of that; 540p and 1080p/720p. When a new version is stacked on top of an old one, Space Saver will remove that original upload on the old version but keep the two encoded versions. This will ultimately cut down on your overall storage going forward, making it easier for you to create more content and not worry about going over your storage limit nearly as quickly.
Also, just as a side note, encodes are never counted in your storage amount.