This dovetail seems impossible, but as you follow along with the steps in this video, it becomes clear how to do it.
A couple notes and tips related to the video:
A push stick is absolutely essential when cutting small pieces on a tablesaw. A large, contoured push stick with a handle that is well above the blade is a good choice. Don’t be tempted to just grab a small stick of wood or use the short plastic push sticks that often come with tablesaws. It is critical that the push stick apply both forward and downward pressure to the piece of wood.
Whenever possible, it is also a good practice to use a feather board when cutting small stock on a tablesaw. If your stock binds or pulls away from the fence it can quickly become a high speed missile. A feather board will keep the stock firmly against the fence and will most likely stop the stock from rocketing backward if it binds in the blade.
The author does a surprisingly good job of cutting dovetails with a hacksaw blade, but it would certainly be easier with a dedicated dovetail saw. A dovetail saw has teeth that are cut in a rip pattern, essentially a line of very small chisels. This is designed specifically to cut wood along the grain, rather than across it. Traditional English-style dovetail saws cut on the push stroke and have a handle roughly perpendicular to the blade. Japanese “Dozuki” type dovetail saws have a much thinner blade and cut on the pull stroke with a handle that is parallel to the blade. A dovetail saw can cut remarkably fine and precise joints. You can cut much more closely to the line without much fear of the blade wandering off the line due to the design of the saw teeth and the control offered by the handle.
When paring to the line, it is a great idea to use chisels specifically shaped for dovetails. Theses chisels typically have a finer blade and are ground to a specific shape. A 1/4 inch chisel ground to a triangle profile is perfect for cleaning out and squaring the base of the narrow cuts for pins in a dovetail joint. Two 1/2 inch chisels, one ground 45 degrees to the left and one ground 45 degrees to the right, are very handy for paring into the corners of tight joints like the one in the video. These can be purchased or made in the shop using regular 1/2 inch bench chisels.