How to get Youtube Start, Middle, End, x Sec Thumb

Question

I was wondering whether the start, middle and end thumbnails are also available in max resolution?

As descriped in "How do I get a YouTube video thumbnail from the YouTube API" the default thumbnail image is available in max resolution through the url:

http://img.youtube.com/vi/<insert-youtube-video-id-here>/maxresdefault.jpg

Start Thumbnail (120x90 pixels)
http://i1.ytimg.com/vi/G0wGs3useV8/1.jpg

Middle Thumbnail (120x90 pixels)
http://i1.ytimg.com/vi/G0wGs3useV8/2.jpg

End Thumbnail (120x90 pixels)
http://i1.ytimg.com/vi/G0wGs3useV8/3.jpg

If possible I was wondering whether there are also thumbnails for keyframes say e.g. 10s available?

• I'm aware that his is only possible in case that the video is available in high resolution