bridge interfaces on separate computers by using tunnel (?)
 

The problem further down.

First the setup:

Location A (fiber, ~100Mbit down, ~50Mbit up):
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Some kind of gateway box from service provider (I can not change any settings on it) give me three regular TP-cable outlets: ip-phone, internet and ip-tv.

Computer A (x86-32, Linux kernel 3.2.7) with two interfaces:
eth0 - directly connected to internet outlet
eth1 - not yet configured (down), connected to ip-tv outlet on "gateway box"


Location B (ADSL, 8Mbit down, 800kbit up):
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Netgear router NAT'ing several computers on local network 192.168.0.0/24 (I have full admin rights on the router)

Computer B (x86-32) on the local network have two interfaces (when/if I insert a second network card)
eth0 - connected to local network (192.168.0.X)
eth1 - connected to tv-box

The tv-box can not be configured in any way.
We can presume computer B will run a recent Linux kernel, I can put whatever on a stick.


Now to the problem:

The tv-box MUST (appear to) be connected to the ip-tv outlet on location A. I want to connect it on location B, but making it appear to be connected directly with a (long) wire to the outlet on location A. I'm guessing some sort of tunnel over internet is needed.

I've tried to connect the tv-box to other outlets and on an internal network (192.168.x.x) on location A (and B) but it refuses this.
It does however work to route the iptv cable through computer A if I bridge the interfaces ( ip-tv outlet <=> eth0 <=> bridge <=> eth1 <=> tv-box ). So what I think I need is to make eth1 on computer A appear to be bridged with eth1 on computer B, sending all traffic on the interfaces through some tunnel:

ip-tv outlet <=> computer A <=> internet <=> netgear router <=> computer B <=> tv-box

The first basic questions: Can it be done? Any severe issues?
The second question: How to do it? (I'm not very skilled when it comes to networking)

PS
I'm interested in a technical solution to the given problem. If I just wanted to get the tv-box to work on location B to watch TV I can simply pay the service provider for a subscription to location B and they'd be thrilled to provide it, and a second tv-box for "free". Also, I will be interested in the technical solution even if the service provider turns out to say "you are not allowed to do that".
DS