A metro can transport higher number of passengers on a given corridor, TM is able to transport less ammount of people on more corridors. The 400 kms of lines in TM plan will put a line of TM within 500 mts of any given point in the city, that is something that can not be achieved in a metro in a long time. The metro originally proposed by Mr. Peñalosa would be part of a regional train system that would connect Bogota to neighboring commuter towns and would serve as metro in the urban area stopping only at high density stations.
Another great thing about TM is the express buses, every station has express buses of some sort, and if you do not find your express bus in your station you go in a regular bus one or two station and catch an express bus that can cross the city with a minimum of stops. Another interesting thing about it is that the buses actually change line, you catch the appropiate bus for the appropiate destination in the city and you do not have to get off, walk into another line and wait again. The only changing that needs to be done is from regular bus into express bus or viceversa.
www.surumbo.com will give you an idea of how the system works in terms of city coverage.
p.d. off course you can change a city on top regardless if you build a metro, the interesting thing about is that cities in Colombia are able to renovate the urban landscape (very important for third world cities as you saw in the video) with the money of the central government thanks to the metropolitan transport law. The pay for 70% of the whole cost of the TM systems, and that includes urban renewal.