Tai Chi Too Delicate and Slow?

Many people are familair with Tai Chi or least the perceived version of the exercise. I have even spoken with people that were of Asian heritage as they had turned away from its possibility as a valid form of cardio-respiratory exercise. The person in fact was at a gym in Hawaii and had a great personal trainer. I did not want to interfere in the relationship that her trainer had with her, so only took in the information and minnimized my comments to her. However, I personally have been flushed as though I had been exercising for a period of time at an elevated intensity much liked jogging or exercising on a treadmill. The Tai Chi exercise was the Tai Chi sword form and later with basic Tai Chi. It was the respiration response that gave me the higher end work out experience, not so many people are able to learn this on their own. A key element for a personal trainer, no matter the exercise, is to guide the client to acheive specific fitness intensities. Yet, the preception to most people and trainers is that this is not possible with this exercise system. I am by no means reverting from my favorites strength weight training and agility training to a single Tai Chi exercise system. Again, this works if you get to know it just as yoga does. I attached a link video of a YouTube Tai Chi video that is anything but delicate and slow. http://www.youtube.com/watch?v=kf44kawWBvY.