If you're looking for something very high end check out a live demo of Elevated X cms
www.elevatedx.com
For a small site the software is usually overkill but a great investment if you plan on expanding. This is by far the most customizable adult site specific product available.
As far as vidcaps - Elevated X gives you the option to browse each video frame by frame and select the image you want to use for video thumbnails.
If you want it truly automated you can specify a default capture point to have the cms automatically capture from a certain frame number when the videos are imported
