I have video thumbnails in my video folder on i tunes and....

Under the Browse button at top right, you will see two symbols:

Four lines stacked above each other = Show as a list of titles.

Four squares = Show as thumbnails.

To see the video's without the thumbnails, do this:

Select the list view in the Search Bar.
It's the second rightmost icon in the Search Bar (under the 'Browse' icon)
(It looks like 4 short lines)

Hope this helps.

M