Summary:
There are two main types of cuts that a table saw blade needs to make: rip cuts and cross cuts. A rip cut is a long cut along the grain of the board, while a cross cut is a shorter cut across the grain.
Rip blades typically have between 10 and 30 teeth and are flat topped ground (FTG) so they can plow through a board. They leave a smooth, clean cut.
Cross-cut blades typically have between 60 and 100 teeth and have alternating top bevel (ATB) teeth that score the fibers of the wood cleanly. Some blades have high ATB teeth for an even cleaner cut.
Combination blades and general purpose blades are in the middle ground, with 40 or 50 teeth. They can be used for both rip cuts and cross cuts, but the quality of the cut may not be as good as using a dedicated blade.
Combination blades have 50 teeth, with 40 ATB teeth for cross cutting and 10 raker teeth with a flat top grind for rip cuts.
General purpose blades have 40 teeth that are all the same, with a high ATB grind for cleaner cross cuts. They are also cheaper than combination blades.
In the video, Steve Ramsey says that he uses a general purpose blade and finds that it gives him good results with almost any material. He thinks that the benefits of a 40 tooth general purpose blade slightly outweigh the combination blade, but only very slightly. However, if you cut a lot of really dense manufactured material like MDF, a combination blade is probably a better choice.