Just had a look at this web part. I was looking for a way to have a page display a random image in a web part. I wanted to select from just some library. This web part sounded ideal.
Well, it’s not ideal. It seems that it will only select images from a picture library called ‘This Week in Pictures Library’. That’s right, I had to change the picture library name. I’m hoping that I’ve missed something obvious, ‘cos that seems really dumb if I’ve not. I mean, what if I want ‘Local Images’ as my library? Does that mean I can’t use this web-part?
I suppose that one possibility is that it’s matching the name of the web part with the library, so I could change them both to ‘Local Images’. I shall test and report back.
My mistake. You can specify another name for the picture library. It’s under the ‘Slideshow > Image Library Name’ option. Kind of obvious. Wonder why this didn’t work at first? Must have had a typo
Comments from my old blog:
Have you figured out how to get it to randomly pick a picture from the library? As far as I can tell, it just picks the last picture added to the library. That’s not very helpful to me.
That’s a good point, I’m not sure. I shall check.
There is an issue with this WebPart. If you have two of them on the same page, and have them pointing to different picture libraries. Then you go and click slideshow on both of them, they both point to the first inital library. Is this a bug?
I don’t know, it could well be. I’ve got to be honest, I spent a half hour looking at one once. I try and take a look, when I get a moment…
Andy Burns' Blog 
Double click on web part (in SPD) to change properties and change “Image Library Name” under “SlideShow” tab, this will change picture library
This shows images only from “Photo Library” main images.
What if I have images in sub folders under that library – then this wont work. How can I give the name of the folder as Look up library then?