I'm sorry I just have to clear something up, Jailbreaking an apple tv WILL NOT let you download movies, tv series or music for free! So you apple ID doesn't come into jailbreaking. What jailbreaking your apple tv will do is give to the ability to install tweaks.
One awesome tool to use after jailbreaking is ATV Flash black. "firecore.com/atvflash-black" which will let you make the most of the apple tv. If you have a lot of media on NAS ATVFlash give you a nice "Media" application that looks great if you spend time to name and place the files right. It also plays most media files not just MP4. ATVFlash also has the ability to let you surf the web, install Last.fm, RSS feeds, weather, plex, xbmc, and different remote applications.
I highly recommend jailbreaking the apple tv it just makes more use of the box.
As for the Jailbreak that was announced to be released on the 1st, I'm not entirely sure about it! I'm hoping that it's true but their has been a few let downs with this jailbreak.