Why conic sections?
11:36
Hindu-Arabic numerals
15:43
Why shadows (almost) always trace out hyperbolas (but it depends on where you live).
15:02
Introduction to Conic Sections
57:59
Viktor Blasjo - Why did Greek geometers construct?
21:27
Introduction to astrolabes: history, design and how they work.
27:26
This open problem taught me what topology is
17:34
How Gravity Actually Works
33:04