In the wake of the recent events in Egypt, the interim government has taken a number of Islamist stations off of the Nilesat satellite - including Hamas' Al Quds TV.
They are telling their customers to continue to watch them through Arabsat, which reportedly broadcasts it with much worse video quality.
But that's not Hamas TV's only problem. According to M.E. Transparent, the Al Quds TV channel was funded via Iran, and Iran has cut off funding, endangering the entire station.
The channel is based out of Beirut with offices in Gaza, the West Bank and (maybe) Damascus.
Hamas has another channel, Al Aqsa TV. According to its website it is also transmitted on Nilesat, but I couldn't find it there, so it might have been pulled as well. .
(h/t Ian)