Here are the collections of sites with math, physics, engineering, and other sciences video tutorials. Some sites also contains non-science videos as well. If you find a site with more than 50 videos, please inform me so I could include it on the list.
Khan Academy – more than 2100 2600 not only for math but also includes other subjects such as economics, chemistry, physics and other fields. The math videos range from adding integers up to elementary calculus.
Brightstorm – more than 500 math videos in algebra, geometry, Precaculus and Calculus.
Just Math Tutorials – more than 1000 videos on algebra, geometry, trigonometry, calculus, differential equations, and linear algebra
Free Video Lectures – more than 700 (excluding Khan Academy’s which they also listed) videos. Videos include single variable calculus, multivariable calculus, vector calculus, probability and statistics, algebraic topology and more. Some are actual class videos.
Math Playground – more than 70 videos for high school mathematics. Topics include integers, algebra 1 and 2, and geometry.
Gresham College Public Lectures – more than 100 public lectures about mathematics particularly history of mathematics, computational mathematics, everyday mathematics, mathematical puzzles, and more.It also contains hundreds of more public lectures in astronomy, biology, physics, other sciences, and other areas such as law, arts and literature, medicine, music, politics, and more.
Two years ago, I attended a lecture of Professor Masami Isoda about dbook, a flash-based software developed by CRICED at the University of Tsukuba in Japan used for creating interactive digital textbooks. The usual practice in dbook is taking a picture (or scanning) of book pages and embedding ready-made tools to construct an interactive worksheets.
The mathematics electronic whiteboard that I have posted here was an empty file of dbook. If you want to know more about dbook, and download the software, click here.
I will make a tutorial about dbook soon, so keep posted.