i screw with this stuff all the time. have dial, 2 flavors of DSL, Verizon broadband/1xrtt. if you get a wireless solution.. witch the TOS (terms of service). Verizon specifically forbids use of their wireless stuff for streaming video of any kind...
but aniways.. here a fairly fault tolerant solution:
have a PC, get a video card that accepts s-video, normal video. cards cost about 50 bucks. for more interesting things you can get boards that have multiple inputs..
search the net for various cameras. the list is endless. see in the dark. IR, color, zoom lenses, pan tilt on and on..
get a box that you can plug a phone line into that will reset up to 4 electrical sockets. get 2 phone lines (second is for the internet connection). plug the first line into the reboot box. plug all of your other stuff into the remaining sockets. this allows you to reboot, restart any of the devices over a standard POTS line. a must if you aren't gonna be there much.
so.. plug your camera's into the board. boot the pc up. get some software that allows you to stream video/audio. the list is endless and much is free. i use remote-view/watcher some. it allows me to broadcast video via a web browser and/or a speialized app that has a client. i put a password on both. i also run netmeeting and terminal server on the pcs. so i can go to the desktop of the pc remotely and control it. so i have pc set to boot up and connect to internet on power reset. worse case scenario i can dial the reboot box and power cycle anything in the remote location.
from this point on it gets more and more interesting. multiple cameras. i have a camera that has 6 position settings i pans, zooms to 6 preset locations with 10 second pasues. I dog robbed this camera from work but it cost 1000.00 retial. a sony ev-100 or similar. i also have an ultra low light pinhole camera and a stand web usb eyeball.
some software that i have acutally will detect motion, start capture, send remotely and email me all at the same time. put this in a room, someone enters, it starts capture and sends email to your phone. if you hide the pc and use a pinhole camera they never know...
then you get into very expensive dome cameras, super zooms, IR zooms...
my lap has the verizon wireless connection. i can be in my car and connect to remote locations and switch cameras and watch from my car or in a hotel room or whatever. next start looking at 2.6 gig outdoor remote wireless cameras that you can stash in the woods across from a suspects location..... broadcast to a remote PC a quarter mile away....
on and on and on..