How to work out where Youtube video thumbnails will be located

How To Calculate The Exact Placement

X = Video length (in sec.)

Y = X divided by 4 or X/4 (in sec.)

Y is the 1st thumbnail.
2 times Y or 2xY (in sec.) is the 2nd thumbnail (poster frame).
3 times Y or 3xY (in sec.) is the 3rd thumbnail.

For example :

x = 364 seconds (video length 6min 4 seconds)
y = 91 (364/4)

3rd = 3 x 91= 273

1 = 1min 31sec
2 = 3min 33
3 = 4.55min\

For more information visit : http://www.squidoo.com/youtubeframe