There's no reason why it shouldn't that I can see. The device use coax cable to send the remote signals down, by the looks of it, but at the receiver end it's converted back to IR.
If you don't need to control it, but just watch, then you would not need the TV link anyway.
HDMI can be used over 25m, and controlled via HDMI CEC, that may be another option. Not sure, there may be HDMI splitters available, not all HD equipment has HDMI CEC implemented, but the picture and audio would be OK.
If the box has component video or composite video/audio connectors on it, you could also send the signal that way instead. A scart to phono adapter with some long cables may also work reasonably well.
The modulator should also work with any SD video/audio source, but not for HD content.
EDIT,
It might be easier to get a 2nd HD receiver as suggested by SMM, generic FTA HD sat receivers can be got from as little as £109, the HD Freesats are not much more.
Screwfix do a 4 way HDMI splitter for about £98
_http://www.screwfix.com/prods/63235/Electrical-Supplies/TV-Range/Amplifiers-Distribution/4-Way-HDMI-Splitter?cm_mmc=GoogleBase
Datafeed
Electrical%20Supplies
4%20Way%20HDMI%20Splitter
There's probably cheaper 2 way ones for about £50 i woul have thought.