I've read, searched and am confused. Let me say thanks in advance for your help.
I want to use my computer to display movies on my bedroom HDTV and my living room HDTV. I thought I could use two cards that support HDMI but it looks like I might run into sound problems. My daughter likes barbie and I would prefer to watch something different ;-) Is it possible to play both movies from the same computer and have them go to different rooms with sound through the HDMI cable? I read this question and it appears that sound is the biggest problem.
The audio won't split that way afaik. You'll need separate sound adapters and point the audio output of the video playbacks to the according sound cards, which probably require running two separate video software. It's not worth the hassle.
You can always buy or build a cheapo PC and have it running in the other room for videos and movies and such. It's a much more efficient solution and you wouldn't have to worry about watching barbie when you don't have to.
Hey, I'm not sure if you're still checking up on this thread but I found something interesting that I never really looked into. It's called multiseat and it might be a good alternative to what you're looking for.
I'm not entirely sure how it works or how to set it up effectively, but it does seem to be a good alternative that not only allow you to watch two videos at once, but do other stuff independently. If it doesn't work for you, then at least this will provide a free bump and hopefully someone can provide you with more info about your sound problem.