It is not exactly for video but for 20" exposure walking , actually I am walking or using a bicycle or a roller-skate
thank you for the link and you explanations the turtke X is certainly good but I thought maybe something more simple will work too, because after 30 second maximum I can stop and seat somewhere
If you're going to be using a 5DII on a hand-held Steadicam style machine, you will need a very light weight lens on the camera, something like a 35mm f2.0 would be a good choice or the 24mm f2.8.
Keep in mind that these machines a very,very sensitive to wind, so if you're riding a bike or roller skating, you'll find operating it without the wind blowing it to be quite a challenge.
For the bike or skates, you might be better off with just a mono-pod with a weight on the bottom. It will look very smooth.