I looked. I liked. Went on a bit, but very good none the less. High voice that chap had...
 

È un castratto moderno di giorno?
 

Although many countertenors apply falsetto techniques, there is a small number who are in a different group (not countertenors but male sopranos - I think anyway - obviously I'm no expert), having unbroken voices and (for one reason or another) having low testosterone levels.

For comparison's sake (albeit on a 100+ year old recording and not an opera singer - instead sacred music at the Sistine Chapel) Alessandro Moreschi is worth listening to. Obviously there are great differences due to music style, individual ability and training, and so on.
 

What a divine voice. It reminds me of vain Senesino, who used to get into terrible arguments with Handel.