[clug] How to Retrieving Android Backup from Google?

[jm]

I'm hoping someone may be able to help me with what should be quite a 
simple task which has me stumped. I've been unable to find directions on 
how to do this with a few searches. I've found a lot of dubious sites 
flogging backup software. May be I'm not hitting the correct search 
terms. More likely I suspect there's just too much junk information out 
there when it comes to backups.

Anyway, a friend has their backed up to Google using gmail account and 
wishes to retrieve a file from this back up without restoring it to 
their phone or alternating their phone in anyway, ie how do you retrieve 
a android back up file from google/gmail?

Note: for various reasons we don't want to touch the phone or add any 
apps to it. Mainly because we don't wish to risk deleting or trashing 
any of the files.

Bonus points if you can tell me what the format of the back up file is.

Thanks in advance,
Jeff.