[Video at Xiph] I need a help, a hint, a link

[Elio Blanca]

Hi, I'm doing the final reviews of the italian subtitles for EpisodeII and I need some clarification.
In the "dither" chapter, I can't get what Monty means at 13:50, I see he's playing with the input 
amplitude when dithering is disabled.
Then, does he mean he's sampling at less than one bit?
And what does this mean? I see, the bar displayer on the ThinkPad shows 1/2 bit, 1/4 bit as 
"amplitude (bits)"? How can this be - sampling or evaluating less-than-a-bit quantities?
Am I missing some valuable notion?
Thank you for any help - or even a wikipedia link  :-)
Elio