using an old mobile phone as a security camera

+1 to what fenderman said ^^

But if you only want to watch the dogs or some other non-critical, indoor activity, look atIP Webcam for Android. It states that it can stream the phone to VLC so it should work with BI as well.

Although I have no first hand experience with that specific app, I used a similar one, ipCam by SKJM for iOS, to stream very well to Blue Iris, using MJPEG.