@JSM1: I happen to be from Scotland (Europe) too. You are welcome to come by and have a look - it takes 1.5hrs drive from Kissimmee.
There are several places in the UK. Lucky Voice has five places
http://www.luckyvoice.com It is partly owned by Martha Lane Fox who set up Lastminute.com
Karaoke-Me is in Bristol
http://www.karaoke-me.co.uk/ and there's another company in London called Karaoke Box:
http://www.karaokebox.co.uk/
Leave me a private message with your email and I'll get back to you.
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@ccsids
1. It's windows based. The way it works is a bit more complex than you describe. You have to add the song files to the folder then open a Media Manager program, which is a kind of database that links to that folder and also lets you assign numbers to the songs. Then you use the Customer Station software in each room to actually play the songs by typing the number into the remote. It's a bit clunky and you will most likely need help from Unify support to make it work.
I should say that there is much room for improvement in the Unify system and it requires a good bit of TLC to keep it going - but if you want to do computer-based karaoke to multiple rooms it is probably the best ready-made solution available. You may be able to find some other companies coming out with other systems on the web.
2. Yes, we have 2000 Spanish songs and will be adding Japanese songs soon.
3. You can buy different formats for the songs you play. Most places in Japan, for example, play videos like the one you described. Unify sells packages of video-type songs but I haven't listened to the sound quality. Sound Choice is good sound quality of course but they do not have videos, only text lyrics.
I'm happy to answer more questions here or in a private mail.