ok, i got curious about it, so did some digging, and found this on a faq entry on a distributor site, in case anyone else was interested....
How it is possible to deliver full 1080p audio/video to multiple screens with "only" a 100BT Ethernet LAN?
The heaviest bandwidth consumer for HD sources currently is Blu-Ray with a maximum bitrate for Audio+Video+Subtitles set at 48Mbits. All other 1080p sources (HD-DVD, Tivo's, Vudu's, Media Center PC's, Gaming Platforms, Digital Signage content devices, etc) come in well below that bitrate. Most of the time even a Blu-Ray movie is not putting out content at this maximum bitrate (30MB-40MB LAN is the typical bandwidth).
Our HDMI over IP units can use up to 50MB LAN bandwidth for sending 1080p to a single receiver, and up to 60MB LAN bandwidth for sending 1080p to multiple receivers (NB the same multicast bandwidth is consumed whether you are sending to 2 or 200 receivers). Most of the time much less bandwidth is needed (especially for Digital Signage content). The ASIC's on the TX/RX units only use compression/decompression to reduce the bandwidth when necessary due to other network traffic, but not if there is sufficient bandwidth available on the LAN to send the full audio/video data stream. While the formal HDMI specification has much more bandwidth defined, that overhead bandwidth is not needed to send perfect 1080p audio/video sources digitally over a 100MB LAN.
While we are not the first company to figure out how to distribute HDMI over IP, all of our competitorís solutions require expensive Gigabit 1000BT industrial switches. Our HDMI over IP solution works fine on a standard 100BT LAN (works with everyday value commonly found LinkSys and NetGear switchers/routers).
A 1000BT device will cost well over £1000 per screen to implement, while ours have a retail price of just £200 per receiver.