It looks like Ancestry has completely changed its internal URL references for images. In the last few days, when an Ancestry search leads to an image (including gravestone photos, pages from books, and those useless generic pictures of ships), the url starts http://mv.ancestry.com/viewer/
(this is new) and the title that displays in the browser is "Media Experience."
Presumably this means that all old Ancestry URLs pointing to images are now broken. As Vic notes, some WikiTree profiles include URLs that point to images on Ancestry of a page from a book that the profile's creator cited as a reference, typically without any information on the title or author of the book. Often when I can see the image, I can use the information in the page as clues to search for the actual source, but that's going to be harder to do if we can't see the image. BOO!!!
I've found that Ancestry provides electronic access to many microfilm images of records that I can't access anywhere else. I try to identify and document the actual source of the record (for example, "Records of Brunswick Separate Church, Scotland, Connecticut, 1746-1846, published by the Connecticut State Library in 1943"; instead of "Connecticut, Church Record Abstracts, 1630-1920 by Ancestry.com"), which should make future retrieval easier if Ancestry changes its URLs for records. However, sometimes it's all but impossible to identify the original name of a record or figure out where it came from.