Yes both is the way. It's often misunderstood and unfortunate terminology that started in Humax land (they obviously weren't catering for modded firmware at the time
).
The main thing to remember is that unprotect and auto unprotecting only changes a small flag on the file that shows itself on the Hummy as "ENC" and replicated to display the same way on the webif as well.
The absence of this flag will trick the Hummy into decrypting the file IF it's copied to a USB drive (or anything that it thinks is a USB drive e.g. the virtual USB drive if you have the package installed). Std Def files do not have this flag in the first place and so decrypt on copy anyway, but HiDef files needed to be encrypted as a condition of being a Freeview HD box. Using unprotect on a file by file basis or auto-unprotect to remove the flags all the time automatically just means anything being copied off the box to USB will be decrypted.
On top of that more cleverness has been employed to use the streaming capability to effect a Download command on the webif (rather than the Hummy on screen Copy command) which will pull the file onto your PC/Laptop and decrypt it on the way.
So the last part is that auto-unencrypt will work on whatever you specify but is best supported by automatically removing the ENC flags on everything i.e. the auto-unprotect.
I put auto-unprotect on there ages ago and forgot about it. Once it's on you can just work on whatever you pull off the box (APART FROM FTP which I personally have no need for these days) will get decrypted whether you use Copy to USB or Download on the webif.
Also to complete the explanation (although I know your OP was about streaming to a PC) if you are simply moving stuff off the Hummy to make room but you only want to play back on the same Hummy then you don't need to decrypt at all - there, now that covers it all I think!!!!!