Instead of copy and paste (which concerns me, because it means you have your seed stored digitally somewhere! )... did you try typing the words in one at a time?

EDIT: Actually, ignore that... it doesn't seem to matter. I tried changing my resolution to 800x600 and you're right, you can't access the NEXT button.

HOWEVER, I think I accidentally found a solution for you... click the textbox resize button... and drag it up to shrink the vertical size of the textbox:



You should be able to see the tops of the NEXT button.