I'm thinking of buying it am I right in thinking if I buy it everyone is stored iCloud? Say I have a music video collection is there any delays with slow Internet playing it?

Can you see all your iTunes content on it?

If you allow home sharing on the Apple tv and your pc iTunes (just a matter of a click on the Atv and your iTunes and it will allow playing of your photos,videos,songs on your iTunes etc through Atv to your tv.I've had no problems with slow internet sped from my pc but I dont use icloud.Jailbreaking will give you extra tweaks etc if you fancy that.

Be aware you can't jailbreak Apple TV 3 only versions 1 and 2 and they go for silly money.

The best solution for ATV3 would be a combination of cloud and some home-based storage. ATV3 doesn't support USB hard drives, so a NAS drive is the usual solution.

To access the cloud your ATV3 will be connected to your router and so to the internet. This will be either by an Ethernet cable (best) or wireless. A NAS drive also connects to your router. This means a wired or wirelessly connected ATV3 can "see" the extra storage space on the NAS.

Your laptop or desktop PC can also see the NAS drive like an extra hard disc. So if you store your music and video files on the NAS then they'll be available to the ATV3 whether wired or wirelessly connected.

NAS drives use far less power than a PC. They're also designed to be left on 24/7, so the files are accessible when your main PC isn't on. It also means that you aren't eating up your monthly bandwidth allowance playing files that could easily be accessed from home.