Can content such as Khan Academy videos be copied onto another device like a computer or laptop
Content may be copied onto another device. However, it is the environment of the target device which may or may not have the capability to display, manage, play… content. This depends upon the requirements of the particular content, which may differ considerably from module to module. One simple example: You would need flash player installed to play the associated media…
The khan academy videos in particular only work with KA-Lite. You could mass export just the videos, but the titles would not make any sense and there would be no organization of them. For khan academy videos alone, please download this package which will work on any device: http://dev.worldpossible.org/cgi/viewmod.pl?module_id=5