Typically you would place either a Slingbox Solo or Slingbox Pro-HD in your house in the US. The Pro-HD will give you a 1080i stream if you have sufficient upload bandwidth (you'll need a steady 3mbps in my experience) whereas the Solo will only give you a 640 x 480 SD stream at best.
You would plug the output from your Comcast and into the Slingbox. The Slingbox is then connected to your router via wired ethernet and will send the video stream across the Internet to your house in France. There is a bit of setting up to do - essentially you have to tell your Slingbox which Comcast box you are using so that it can correctly control it. The way that works it that you will place an infra-red transmitter (supplied with the Slingbox) near the IR sensor on your Comcast box, which then plugs into the Slingbox.
Then, in your house in France (or indeed anywhere), you can then view your US channels via the web player, or on an iPad, iPhone, Android device etc.
If you want to view your US channels on a proper TV in France then you have a few options:
1) plug a computer into the TV, use the web player and switch it to full screen mode. The downside with this is that to change channels you have to fiddle about on the computer so it might not be the best experience. It is possible (and I have done this) to configure up a computer (I use a Mac Mini) in conjunction with a Harmony remote control and be able to control the web player using this, but it's not a trivial task and took me ages to write the necessary scripting etc.
2) get hold of a SlingCatcher. Sadly, these are no longer made or supported, and will set you back about £500 on eBay. However this will give you a hardware remote control and a much more user-friendly experience. You can literally control your EPG using the supplied remote and it's as seamless as it gets. The downside, if you are intending to stream 1080i, is that the Slingcatcher will only support 1280 x 540 at its maximum resolution, so somewhere between SD and HD. However, in my experience, and with sufficient bandwidth (as I say above, 3mbps stable upload in the US) this is a very good solution. I have collected several of these myself, and it's a crying shame, in my opinion, that Sling haven't continued to evolve it to support proper HD and have instead concentrate on writing apps for "Connected Devices" instead. But I guess they have their reasons...
3) talking of "Connected Devices" - get hold of a Boxee box or Logitech Revue. These devices have Slingplayer applications, though from what I can tell there has been a mixed reaction to them so far. I've not experienced one at first hand though so these may be good solutions.
4) if you have an iPad and an Apple TV then you can buy the Slingplayer application for iPad and then use Airplay to stream it to your Apple TV which is connected to your TV. I'm unsure what resolution the "High Quality" setting on the iPad gives though, and how it compares to 1080i or the SlingCatcher's 1280 x 540 but I imagine you'll get something at least or better than standard definition. It'd be good if Sling could update the iPad Slingplayer application to support 1080i now that the new iPads have sufficient resolution.
There have been rumours of other Slingplayer apps for devices - there was one touted for PS3 at one point, but that seems to have gone quiet. I'd personally like it if they could create one for Apple TV but that seems unlikely while Apple have the Apple TV platform locked down.
Note that I don't have experience of additional Slingbox-based devices in the US - maybe there is one that will integrate your Comcast functionality with a Slingbox (they call it Slingloaded I think) but I don't know.
Hope this helps!
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