@cl4rckk3nt
They allow 2mb per product in the derive chain, so if you chain 3 products, then you can actually get 3 * 2mb (6mb), into a single product. The example product you gave, chained like 25 products together for a total of 64mb in a single product. It's as simple as:
1) Create a 2mb music product
2) Derive from the product you created in step 1
3) Add 2mb more music to the product
4) Derive from the product you crated in step 3
5) Add 2mb more music to the product
6) Derive from the product you crated in step 5
6) Add 2mb more music to the product
7) Derive from the product you crated in step 6
.... I am sure you can see the pattern. Keep it going.