Because ballroom dance videos are mentioned so often on this site, I think that it would be worthwhile to take a look at this medium and consider its value to the student of ballroom dancing.
First, let's consider the storage media available for videos. Essentially, there are three: tape (usually VHS), disc (usually DVD), and hard drive (various protocols). Tape provides sequential access while the other two media allow direct access. For this reason alone, tape is the least desirable medium for storing videos. DVD is the best medium.
For the purpose of this discussion, we need to categorize ballroom dance videos according to their content.
The first and most readily available videos are recordings of performances - competition and demonstration - by famous professionals, usually champions. We'll simply call these performance videos.
Next come instructional videos, recorded demonstrations of individual syllabus figures accompanied by discussions of technique. Instructional videos are less accessible than those of the performance variety because they usually must be purchased. This site is the only one I know that provides free access to video instruction.
Finally, there are the videos that we make when we record our own performances or practices. Typically done with camcorders, these can be viewed immediately and even downloaded to a personal computer if the necessary features are available. We'll call these personal dance videos.
The entertainment value of a video is generally the inverse of its instructional value. Watching Gozzoli and Betti is enchanting but the instructional value is virtually nil.
Instructional videos are, obviously, not very entertaining because the dance sequences are usually quite short. The discussions of technique are these videos' most valuable feature. Instructionals videos are useful to students for showing them what they should look like when they perform the basic elements.
Unless one is an irrepressible egotist, personal videos have no entertainment value at all (at least to the folks appearing in them). On the other hand, they have the highest instructional value simply because they show students exactly what they are doing and not what they think they are doing.
No video, however, can show student HOW to dance. As has been stated many times on this board, there is no substitute for a good dance instructor.
No matter how good and instructor may be, none can really show students exactly what they are doing on the dance floor. Videos can be a very valuable learning tool but they are always just a tool.
Also, as I've pointed out in previous posts, seeing yourself can be the best motivation to lose those extra pounds that slow you down.
Good luck.

jj