Ok I got it working. For anyone who wants to add their Blue Iris cameras to the presets of Cast Web here are the steps:
You will need to manually edit the preset since the generator doesn’t have any content types other than video/mp4 and audio/mp3.
set your MediaType as image/jpeg
Make sure you have the web server enabled in Blue Iris
the mediaURL will be http://BLUEIRISIP:PORT/mjpg/CAMERASHORTNAME/video.mjpg
All the other stuff in the preset is optional info.