Unique Values From a Matrix

Question

I have a spreadsheet that looks like this:

Column A | Column B
         | An unimportant value
1        | Value 1, Value 2
2        | 
3        | Value 3
4        | Value 3, Value 1
         | Don't want this
1        | 
2        | Value 5, Value 6, Value 2
         | Don't want this
1        | 
2        | Value 7

I'd like to extract the unique values from Column B that have a value in Column A and end up with

Value 1
Value 2
Value 3
Value 5
Value 6
Value 7

Example spreadsheet: https://docs.google.com/spreadsheet/ccc?key=0AvB0HQO9X_ExdE1TZENMWDFlZkRhTThpcVlGMVNybkE

So far I have a formula that splits up that column and spits out the matrix of values: =arrayformula(split(FILTER(B3:B, A3:A>0, LEN(B3:B)>0), ","))

I've run into two problems:

1. I can't get the unique values from the matrix that is output -- UNIQUE only lists unique rows.
2. For some reason the first row split only gets the first value. Notice that Value 2 is never mentioned in the output in the example spreadsheet.

Answer 1

Possible but may require some 'compromising':

=arrayformula(right(split(FILTER(B3:B, A3:A>0, LEN(B3:B)>0), ","),1))  

in D1 to F10 does find the 2 (which should have been 'underneath' where you put your formula for the purposes of your example) - it also strips out Value, though this could be added back later if required.

in say G1 and copied down to suit:

=arrayformula(LARGE(value(D$1:F$10),row()))  

then with all your values in a single column, in say H1 and copied down to suit (upto #NUM!):

=unique(G:G)  

The results will be in reverse order from as shown by you (sort?) because of use of LARGE rather than SMALL because if positive values only all the 0 would have come first and there are quite a few of those.

Concatenate results with ="Value "&H1 etc if required.