[Plugin: Video Thumbnails] Thumbnail Width

Hello
Sorry but my english is not great
i will try to tell what is my problem

i am using nivo slider in my web side.
http://www.ozgurkalyoncu.com

this great plugin video thumbnail helps me to get youtube thumbs.
but problem is width
they are not as big as my nivo slider
and it seems really bad
how can i set it ?

http://ww.wp.xz.cn/extend/plugins/video-thumbnails/