How do I create a video of typing math symbols
You could be clearer about what 'on my video' means. Does that mean: composited with other moving pictures in your video; or does it mean: in a sequence all by itself that's edited into your video? Or something else? And what video tools can you use?

For compositing use a compositing tool like Adobe After Effects. After Effects would also be perfect for building the 'typing on' sequence of symbols that you want. 

If you don't have access to After Effects, why not build your sequence as a set of Photoshop layers which you can then export as an image sequence. Import that sequence into Quicktime (Pro), then re-export as a .mov using a codec that makes sense for you project. If you don't have access to Photoshop you can still do this with any cheap graphics software. Just 'manually' output identically sized images and name your output files sequentially. Tell Quicktime Pro to import them as a sequence.

Another idea:


create a single good image (similar to the ones that you provided links for) of the complete expression or equation that you want to 'type on' the screen.
import into Adobe Illustrator or PhotoShop.
create a series of white 'masks' (just rectangles) to cover each term in the expression or equation) and put each one on it's own layer, in the sequence in which you'll want them revealed. 
De-select the eyeball on each layer, in sequence, to hide the 'mask' for that layer and reveal each term in sequence. Run Camtasia as you do this and you'll have the 'typed-on' movie you're looking for. You could pre-record your audio so that you'd have a good sense of timing for the reveal of each term.