Plugging the MB to the TV is probably the easiest, but it may not be the ideal.
There are a few devices that are basically hard drives with composite/s-video outputs. Macally makes one. You would store your video onto this hard drive and then connect the HDD to the TV. An included remote would be used to navigate.
My dad has a DVD player that has a separate slot for an external HDD. It plays all sorts of formats. The HDD can be connected via USB for up/downloading. Not sure what the HDD is formatted as, but I'm sure it's not HFS+. Mac users may not be able to write to it, which would limit it's usefulness for many of us.
Yes, the adapter that Vader linked has both s-video and composite outputs. Keep in mind that you're on your own for audio ...
Actually for audio, just get a mini-jack by stereo RCA adapter and then a standard composite stereo audio cable (Red/White). Most TVs (if not all) that have composite/s-video inputs will also have RCA audio inputs as well.