Interesting. Cartagena is a cool place and I'd recommend going and spending more than a cruise day there. A lot of history with Spanish Inquisition, slavery, and shipping control. I'd say from my experience there are really 3 parts of the city, two of which were covered. The old which is in walled portions including Getsemani, Boca Grande and other more modern locations, then the areas to the south, which probably is were most people live. It's a huge port as well, considering it's proximity to the panama canal.
I kind of thought the video would talk about the growing tourist industry there and then some of the other stuff seedy stuff. Its still Colombia. You will be offered to buy drugs, and prostitutes are easy to find. Many from Venezuela. The girl in this video might have been one? I'm not certain. I heard many of the 'locals' one would meet in a bar or club will eventually ask the foreigner for money before heading to the hotel. Its very much affordable, and they have some great food options. Food there has a Caribbean influence, but also what you'd expect from Brazil or Argentina. Some really good red meat options there, and for half the price you'd find here. The old town is a historic site so many of the building exteriors are maintained, only to walk in and be amazed at the inner details. The Spanish colonial architecture is probably hard to find on this side of the planet. The cruise industry has probably helped inject money there more than anything.
Note the population of Cartagena is a bit different than maybe your stereotypical Colombian (ie Shakira). Due to the harbor, and local farming, many of the residents are descendants of slaves and that's reflected in the locals. I only point this out because it was pointed out to me on the flight there, and then explained on a walking tour. Everyone was very friendly.