> this version has the tugging on tails, but not the picking up and accordioning of the mother, so it's a falsified version

I wondered if that puts the Corridor version in jeopardy in any way, given that the version they have posted was produced many years later. In my few minutes of research, it seems like the answer could be quite complicated and it would depend on whether or not the censorship process exceeds the threshold of originality.

For example, I imagine if Disney had engaged in a significant colorization process of the original footage in the 50s that the resultant colorized footage would still be under copyright today.

I do think that the process of removing footage could be considered a sufficiently creative endeavour. For example, if Kubrick released a re-cut version of Odyssey 5 years after the original, I would not expect the re-cut to enter public domain until 5 years after the original (even if the only difference was removal of certain scenes). If anyone could argue that censoring a film constitutes as an editorial creative process and thereby should be granted copyright protections, it's Disney.