I can understand why CX does ads in Y but it just feels cheap doing it in J/F, especially a long haul premium cabin where tickets sell for $10k/$20k return full fare.
Though to be fair, SQ and LH does it in their long haul F cabins too.
Ironically, I don't think United has ads in the beginning of their AVOD movies in their J seats. However, I'll take the ads and fly CX/SQ/LH first any day.