One particular part of the UI is confusing.

1. I have entered the URI-M https://wayback.archive-it.org/2950/20120110014403/http://OccupyHouston.org/es and clicked "Calculate # of Thumbnails"
2. I then clicked "Calculate Unique"
3. I am confronted with instructions that state "The options shown below are based on the amount of difference between the mementos." and am presented with 3 buttons as shown in the screenshot: "2", "1", and "Generate Thumbnails".

The instructions in step number 3 imply that "2" and "1" provide options. After some consideration, I assume that they are paginating something, but I've clicked on both and see no change. Clicking "1" changes the message beneath the buttons to "(estimated 1 minutes to generate)". Clicking "2" changes the message beneath to "(estimated 2 minutes to generate)". What do clicking them change? Do these buttons alter the amount of time dedicated to generating thumbnails?

My suggestion is to be more explicit in the instructions about what is expected of the user.