Most symbolic math programs can output the results as both programming language code (C, Fortran, etc) and as TeX formulas. For instance, Maxima:
I generated a quick expression (Pade approximation of a Taylor expansion of a symbolic derivative, whatever), and right-clicked on it, selecting "Copy LaTeX', to receive:
In the old DOS days it was well nigh infallible. These days it depends on the font you're using - some seem to work and some don't.
Again in the old dos days (don't I sound like and old fart??) you could use this trick to get the single and double line box characters, and use them to make great looking menus.
That video is great! For math formulas, you might find this useful. Microsoft OneNote (bundled with Office) has a nice “ink to math” utility. You can just draw a formula freehand using your mouse, highlight it, and convert it to a formatted equation. You can then insert that into a Word document if you wish. There is also an “ink to text” utility for converting freehand text to print.
A lot of these tricks have been around since time began ... the problem is that newbies don't know them...
...I think we would all be surprised to discover all of the little tricks and back doors that are available ... if only one knows where to look...
The ALT+ trick has been available since the DOS days. I use it all the time to type the degrees symbol (e.g. 25°C - ALT+0176), the Greek micro as a prefix (e.g. µHz - ALT+181), a plus or minus symbol (e.g. ±3dB - ALT+0176) and more. Works in almost all PC applications.