It will make flour, but it's very poor flour. Essentially extremely fine grain dust with some chunks of cracked grain. Good flour mills are available and are very good if you make your own bread on a regular basis. With a proper flour mill you can set the fineness of the flour.Mildly disappointing to hear, but I'm really only interested in doing it as an experiment, so probably not worth buying a mill. I'm happy enough store bought flour. Is there an advantage to making my own flour?
Depends what you want. I don't want to eat white flour. It has no nutritional value and no flavor. Unless I'm away from home and have no choice, my bread is always 100% whole grain. But store-bought whole-wheat bread flour (as distinct from pastry flour, which is made from soft wheat and not suitable for bread, which requires hard wheat) is always a coarse grind. That coarse-ground flour makes a heavy dough, not very elastic, that does not rise well unless you add a fair amount of white flour.
To make a nice elastic dough you need a finely-milled flour. And I've never been able to find finely-milled hard (bread) whole-wheat flour in the store. I've found finely-milled whole-wheat pastry flour. But as I said, pastry flour is made from soft wheat and is not suitable for bread. (Hard wheat has more gluten.)
With my own flour mill (steel blades, not stones*) I can mill my grain as fine or as coarse as I like. And with a finely-milled 100% whole-wheat flour, I can make an excellent, elastic dough that makes great bread, without using any white flour.
Using your VitaMix you will get a poor quality flour that contains much that is too fine and much that is too coarse. But if all you want to do is have a go at milling flour and baking a loaf of bread, you can certainly do it. Actually, I'll say go for it. But if you find you like bread-baking, then I recommend getting a proper flour mill.
* "Everyone" seems to think that stone-ground flour is better. I think the reason is that large commercial mills have stones with channels for water to cool the stones. But a home flour mill that uses stones will not be able to make a sufficiently fine flour. It comes out too coarse, which is okay if you just want to add some texture to your bread, but by itself makes a poor dough unless you use white flour. I had a stone mill. But my steel-blade mill does a much better job. And in the small quantities needed for a couple of loaves of bread, it won't get hot enough to be a problem.
I don't make bread any more, though. Fresh bread is just too much of a temptation. I cannot keep myself from eating about half the loaf as soon as it's cooled enough to break open.
Another advantage to milling your own flour is that you can add other grains for flavor. Rye, barley, brown rice. You can also add legumes. A little bit of black-eyed pea flour gives a nice flavor. With a steel-bladed mill (or your VitaMix) you can also make corn flour. Don't put corn in a stone mill though, because it will gum up the stones and plug up the mill and you'll have to take it apart and clean the stones.
It's really easy to make good bread. Kneading the bread is a bit of work, but other than that it's mostly a few minutes of mixing, and then a lot of waiting. I generally made a sponge in the evening (a few minutes of milling, a few minutes of mixing) then let it sit overnight. Then in the morning add the rest of the flour and knead for maybe ten minutes (don't actually remember how long). Then let it rise in a warm, moist place for a while (an hour? I don't remember) and then bake it. Start to finish 12 to 14 hours, but actual work time, maybe 20 or 30 minutes.