I don't understand why some of the examples shown her have a minus sign in front of the field name.

Because in a shuffle-by-year you want LOW numbers (years) first; in a shuffle-by-most-often-played you want HIGH numbers (play counts) first.

I also don't understand why RANDOM looks like a field name.

Because it acts just like a field name -- one with a different random value each time it's evaluated.

And why one of the examples have RANDOM only and others have other fields. Why do some require more parameters than others?

The one with RANDOM only, will shuffle the songs in completely random order. The ones with other parameters, take those factors into account too when shuffling the songs.

Can you really do math expressions on the line as was suggested?

No. But Bonzi's suggested math expression, maximize(plays-2*skips)), is the same as a shuffle "PLAYS=1,-SKIPS=2".

Why 32000 and 2000? Isn't that the same as 32 and 2?

Yes, it is.

And this statement...

Then, for each track, the number of plays is multiplied by 32000 and added to a random number (1-32000) is multiplied by 1.

... confuses me becuase the word "is" gets used twice in the same breath.

Sorry, the second "is" shouldn't be there.

Is the number multiplied or added?

Looking at it now, it would have been clearer to use "*" instead of "=", and "+" instead of comma. So instead of

-YEAR=32768,RANDOM=1

please read it as

-YEAR*32768 + RANDOM*1

Hope this clears things up a bit...

Peter