Google Sheets – How to Return Unique List of Text Pivot by Query

I'm trying to mimic a pivot table behaviour where you would grab all distinct values from Col B and, by each of those unique Col B values, you associate all each respective values, that must also be distinct by each unique Col B.

Here's my data set:

A               B
y_13_other  4601032322-video
y_13_other  4601032322-video
o_06_other  4601032322-video1
o_06_other  4601032322-video
o_06_other  4601032322-video2

The final result should be:

 B                   A
4601032322-video   y_13_other
4601032322-video   o_06_other
4601032322-video1  o_06_other
4601032322-video2  o_06_other

I've tried the query with Group by, but it doesn't seem possible to aggregate by text.

=QUERY(A2:B5;"SELECT A,B group by B")

This would need an AGG, and it only seems to work with numbers.

Another option I thought was to pair a query with vlookup, but I haven't managed to, is there a way to do this, even without the query formula?

Note: I don't know how many rows A or B is going to have and don't know their future names, it would have to work dynamically.