This way of cleaning carpet is used in some business and in residential homes some times. It is know as a maintenance cleaning most of the time it is done when carpets get a lot of traffic and need to be cleaned often.
This method of carpet cleaning what happens is that the cleaning agent that is applied to the carpet. Incapsulates the dirt that is in your carpet. Then after it is dry when you vacuum the dirt comes off the carpet living your carpet clean and fresh.
First as any carpet cleaning it should start with a very good vacuum to remove any loose soil that is on or in the carpet. After that a cleaning agent is applied to the carpet. Then the carpet is adjatated with a buffer or a counter rotating brush(as seen above). After that is complete the carpet is left to dry completely.
VLM carpet cleaning usually cost less than steam cleaning carpets. The reason that it is less expensive is because it takes less time for a technician to preform the work. It also doesn't require a lot of expensive equipment as steam cleaning does.
This cleaning process is really designed to be only used for cleanings in between steam cleaning it doesn't replace steam cleaning your carpets. Remember that carpet manufactures warrantee requires your carpets to be cleaned every 12-18 months.