You will need a HDMI to RGB converter box (component or scart depending on your video equipment).
Make sure it comes with an external PSU since the Pi isn't designed to power devices directly via the HDMI port.
There is no cheap solution converting HDMI to analogue video is quite a complicated process.
To be honest I don't see any benefit for converting HDMI to RGB when the resolution is no better than composite video.
Granted composite isn't great but if your watching videos on and old CRT type TV the image quality should be more than adequate.