Videos accompanied by documents—document-based videos—enable presenters to share contents beyond videos and audience to use them for detailed content comprehension. However, concurrently exploring multiple channels of information could be taxing. We propose SwapVid, a novel interface for viewing and exploring document-based videos. SwapVid seamlessly integrates a video and a document into a single view and lets the content behaves as both video and a document; it adaptively switches a document-based video to act as a video or a document upon direct manipulation (e.g., scrolling the document, manipulating the video timeline). We conducted a user study with twenty participants, comparing SwapVid to a side-by-side video/document views. Results showed that our interface reduces time and physical workload when exploring slide-based documents based on video referencing. Based on the study findings, we extended SwapVid with additional functionalities and demonstrated that it further extends the practical capabilities.