That would be correct for a raw sensor dump - it never leaves the camera, as it actively works differently in video and camera mode. It delivers a partially compressed stream in whatever mode that is, otherwise there would be no HD cameras, at 250M/s the data is too much for any portable storage system (even a SSD).

Also, there is no way that tiny unshielded connector phone cameras or video cameras have can take 250M/s. that would mean at least a 2Gb link.

Not even DSLRs deliver uncompressed raw data, all real life RAW formats I know are compressed. My A200, e.g., delivers 10M at 12 b/plane (48 bit, 6 byte), that's at least 60 MB of data, in a RAW 5-10 MB in size.

It's not entirely impossible to do it like that but I don't know of a single device (other than dedicated capture systems) that delivers raw data like that. Actually, I do, but it's way, way beyond the scope of this discussion.