What is a streaming file?
The "streaming" file extension is ".m3u8" and it is a bit complex because it can support multiple quality levels in a single file. For example it could point to the large (1920) and small (720) sizes.
It cannot be downloaded in a straightforward way like an MP4 file can because it is really a pointer to other files.
The word "streaming" means that the entire video does not need to be downloaded before playback can begin. This is because videos are chopped into "chunks" that can be just a few seconds of the video, which can be loaded must faster than the entire video.
The Castera Use Agreement states that each user must take responsibility for their use of downloaded files and that they will only be used for personal purposes.