I'm frankly amazed (and amused) that the video of Disney re-use is still generating comments after more than a week. I was certainly aware of how heavily Disney re-used animation during the Reitherman years. The video didn't surprise me so much as wrap things up in a neat package.
Thad Komorowski has created a similar video cataloging Bob Clampett's history of re-use, some of which I wasn't aware of.
Anyone who has worked in animation production knows the twin pressures of budget and deadline. While nobody has brought it up, Chuck Jones re-used animation multiple times within his half hour TV specials, including The Grinch and Riki Tiki Tavi. We can argue over a director's motivation and judge whether the end result has value or not, but I don't doubt for a second that given the opportunity, every director would opt for new footage instead of re-use.