Hi,
If you want to store it on the device you need to transfer it from the desktop. You can however, stream from Google, Amazon, HBO Go, and various websites: abc, cbs, etc. If you decide to download a couple of good movies to the Playbook I suggest DVD Catalyst. They are awesome and their customer service is amazing.
As for music, I suggest you try the 7digital app. It is cloud based but it can download to your Playbook, as well as your PC, phone, etc. It knows who you are so it does not charge you to put the music on multiple devices. I believe there is a limit of four devices.
Your tablet takes great video. I hardly watch movies but I show and watch video of my kids all the time. Enjoy.
