The video is always linked, but the audio file can be embedded or linked. You can check if slide has a video using the code in this thread.
<A href="https://forum.aspose.com/t/102715</A> </P> <P>You can check, what is rendered by getting the image of slide. Mostly, it is the video frame shape.</P></FONT>
Yes, it is possible.
Both VideoFrame and AudioFrame has FileName property, which you can read/write in runtime.