Cast iron drain lines fail from the inside and from the bottom of the pipe first, where waste sits against the invert. Scale narrows the bore, then the invert corrodes through while the top of the pipe still looks reasonable on camera.
That failure pattern is why a cast iron line can pass a casual inspection and still be at the end of its service life. It is also why cast iron problems often present as recurring slow drains rather than a sudden blockage.
Interior cast iron in older Wichita houses runs under the slab or through the crawl space, and replacement is disruptive work. We scope it honestly rather than starting and discovering the extent halfway through.
Technician insight
Look at the bottom of the pipe on the camera footage, not the top. Cast iron that looks fine at twelve o'clock can be gone at six.