You could theoretically get a small computer big enough for a video capture card, or even use a low resolution USB video capture. Hook your Xbox360 or PlayStation 3 to the audio/video input of video capture card. Let ffdshow process the video window (showing xbox/ps3) into amBX effects.
You could keep using your existing HDTV/home theater for the video... the PC is simply mirroring the picture/audio into its video window in a hidden manner, solely for amBX to process in the background... Easiest is if you're already using analog audio/video connection that you can easily split out to be used with the video capture card (for sole purpose of amBX processing). If you're doing HDMI and want to keep using your native HDTV...For devices that refuse to output simultaneous video through HDMI and composite outputs, you may need a HDMI splitter (distribution amp) and a downconverter (HDMI-to-analog converter), to hook to the input of the video capture. Make sure it also converts the audio too, if you want the audio processing included.
You can use a hidden computer next to your TV/xbox/PS3 to process amBX effects for Xbox360/PS3....via the capture card trick.
Composite -- easy (use RCA splitter)
Component -- easy (use three RCA splitters)
S-Video -- easy (need S-Video splitter)
HDMI -- difficult but possible (unless device also simultaneously outputting analog audio/video)
This will convert your PS3/Xbox360 into amBX compatible effects.
Yes, another $200-$300 for a basic PC next to your home theater, but it would allow amBX to work with your PS3 or Xbox360... Even blu-Ray too players, probably.
It's a little Rube-Goldberg, but it would work in an "ambilight" manner, like watching a DVD movie.