I'm not at all satisfied with the thumbnails exhibited for my Mark Twain chapters. My preference would be to use the opening frames of the videos but that is not how things are done. I did run across what looked like a very hopeful calculation. It reportedly tells you exactly which frames are used, you have a selection of three. The calculations work as this: Obtain the length of the video in seconds (X); the first thumbnail should be located at X/4 (Y) or at exactly one fourth of the video; the second frame at Y*2 or X/2, or at the midway point of the video; and the third at Y*3. Sounds good but it doesn't seem to work for me.

Earlier I found posts stating that the frame used is the exact center so I spent the morning reworking the video for Life on the Mississippi, Chapter 6 (Part 1). The thumbnails present scenes from the Second Life session whereat the reading took place and this type of footage is the majority of the video. However, illustrations from the book are spliced into the Second Life footage and it is these I'd like to have used for the thumbnails. In this particular case the second and third frames should be such illustrations but they are not. This is frustrating as I'd like the thumbnails to actually represent the content of the audio track. I don't know if the first frame calculation is valid as I've run out of time to play with it today put as the second two fail it is dubious.