I have been messing around with a few settings in TMPG but I would like to know what the following options actually mean and do, so if any one can help...thanks:

Rate control mode - what difference oes it make selecting 2 pass VBR as I hae seen alot of people mention this.

Motion search precision - If i leave this on motion estimate search as opposed to High Quality or above, what am i likely to miss out on (As far as I can see it increases my encoding time by an hour or so)

And finally if I select Save analyzing results of multi pass VBR to cache... what does it do.

I know that all of these options have tool tips that give some explanation but I still dont fully understand it all

Thanks in advance