I watched/listened to your video and can tell that you have an airway blockage somewhere. What happens is that if there is any blockage of airflow, there is a valve, which opens up. When it opens up, air is allowed to pass, so that enough air continues to go through the motor. If this did not happen, the motor would soon overheat; causing possible damage to the motor. This feature is on some other brands as well. Other brands usually have a thermal shut off. If the machine gets too hot, the vacuum cleaner will shut off and you would have to wait for a while before turning back on.
What you are going to need to do is check for any blockage. Be sure to check the hose, then check the filter in the dirt bin. Remove the hose and turn the machine on. Is it still doing the same thing? If it is, then the hose probably is not the problem. Another way to tell is if you turn on the machine, then remove the hose. There should be a big difference in the airflow and the sound that it makes, if there is a clog in the hose. That model looks to have an inner filter. The inner filter can get to the point where it no longer will allow air to pass through. You can remove this inner filter, then turn on the machine(if the vacuum will allow you to do so), without the hose attached. Is it still tripping the valve? Make sure that you are not vacuuming up anything without the filter installed.
If that does not fix the problem, then you will have to check the airway from the hose connection to the dirtbin. This will be harder. The valve itself could be defective, but highly doubt it. Check the hose and dirtbin filter first, because that is the common areas for blockage of airflow.
I would like to suggest that you read the manual, because it will tell you how to maintain your machine.
This message was modified Oct 21, 2012 by Mike_W