What is the source for this statement?

This statement could include more nuance. Large publishers have successfully sued volunteer, third-party translators because that act was actively damaging their market for their release of translated versions. But a third-party caption available on an Intranet (of perhaps limited duration) for a public video that is used for accessibility purposes would most likely meet "fair use" or "fair dealing" criteria. To my knowledge, there has been no litigation under those protections in North America. Perhaps faculty should be cautioned about the lack of legal clarity about the issue, so the less risk-averse of them can consider the issue fully. Having said that, seeking permission would still be the recommended first step.

Mixing explanations of UDL and accessibility often lead to a watered-down version of each. Here, there is little discussion of the philosophy behind UDL, just a definition and then a list of tools that are barely relevant to UDL. Even when a recommended practice is mentioned, such as supplying digital copies of presentations ahead of time, no purpose is given. So, if one knew nothing about UDL before reading this section, one would likely not come away with any clear idea as to what it is or think that it is about technology adoption. I think it could be dropped.

The video below on "Making Sense of Universal Design for Learning" is not closed captioned.

The first presentation "Accessible APA presentation" has extra animations that do not work with a screen reader. The screen reader reads all the slide content, regardless of animations. Then, the user has to press "Enter" several times to get through the animations to the next slide.

The video below should be captioned, even if the caption indicates that only music is played throughout.