I've seen it mentioned that hackers can create AR images around a place of business to deter customers. I've also seen it mentioned that you can hack the AR overlay and place items around town that other people may mistake as real.

What actually needs to be hacked for these things to occur? And what software would you need to loop video feeds in AR?

You can physically put tags that with a public ARO or you can hack a node in or near the place and attach a public ARO to it (I don't think there are any specific rules about "attaching an ARO" to a node, but I guess it can be done).

The Edit program is all you need for editing things, be they videos or AROs.