Seems fine in its own terms, but doesn't really do what I want. It works by making a source 'visible' after a specified delay for a specified period of time. However, this is not 'visible' in the OBS sense, which has to do with activating/deactivating the source. As a result, a problem arises with dynamic graphics, like scrolling text.
So, for example, if you have a source that scrolls a block of text in from the bottom of the window and out of the top of the window that takes 5 seconds to complete, using the script with, say, a 10 second delay will result in nothing being shown (the text has already scrolled out of the window 5 seconds before the source was made 'visible').
What I would really like is an activation timer, rather than a 'visibility' timer.