If you scroll down in this forum, you will see one called "Another Aussie built router" or something like that. Read through it, he uses rack and pinion and does really nice work. As to whether there are a set of plans out there, I do not know.
One thing you should know however, is that if you use rack and pinion, you will be able to achieve speeds like you saw in the video. That is the nature of R&P and belt drives, they can be very fast.
If I were running a business that needed a large router for cutting doors, etc and I did not want to pay the higher cost of off the shelf stuff, I would draw up my plans after doing a lot of research, then have a smaller machine shop do all the grunt work, like making the table, fabricating some of the sections needed, etc. Then I would purchase the parts (rails, bearings, etc) and do the assembly work. If I were using steppers, I would do the electronics too. If I used servo's, then I would find an electronic guy to do the tuning of the drives required.
Right now, I am building a medium size (which to me is a 28 X 38 machine). I am doing it all since I have the time. And it is definitely a homebuilt, MDF, hard maple, etc.
Good luck on your endeavor!