Content moved to another profile will not work. Anything within a PIRS archive package, Demos, Downloaded Icons, and Themes all reside in this category; will be signed to its original profile and will not work without the original owners profile as well.
If your buddy wanted to share his profile and his content, you could do that.
Only saves may be moved profile to profile, console to console.
I borrowed a friends HD and loaded it up with demos(cause he has no i-net), and I don't have a premium. I boot my xblive from my profile on my mem card. So I am wondering how this is possible since my profile is not on his hd and the demos work fine. So it seems its signed to the hd or other device and not the profile itself?