Sometimes I feel like doing “making of” -animations like this:

Photoshop CS4 (Extended) has some gif animation tool and it has some automatic settings to do frames from layers. Problem is that for this purpose the first layers should also stay visible. So is there any way to automate it so that the layers below would stay visible from their starting point to the end? When there is a lot of layers it takes some time to adjust the endpoint of everyone. Or is there some other easy way of doing these?
Thank you in advance. 


But as mentioned - this is not an issue with couple of layers (like in example), but sometimes there are plenty and one might consider changing animation settings after done all the work (when work must be done again). Just trying to reduce “not so creative” part of work.
So if anyone has some ideas or some other tool to make nice animations describet, I’d like to know.