Allocation of impairment of CGU

Hi, in the last videolecture of chapter 7 the tutor says that we should allocate impairments of CGUs as follows:

1. Specific asset
2. Goodwill
3. Remaining assets (pro-rata),

but in the BPP workbook, page 97, the following is saida about allocation:
a. To any goodwill allocated to the CGU
b. To the other assets of the unit on a pro-rata basis based on the carrying amount of each asset in the unit

It doesn’t mention the specific asset first, and in fact, in an example on the essential readings where a non-insured asset is destroyed in a terrorist attack, it first allocates the impairment in full to goodwill and the rest to non-current assets.

Can you explain this, please?