I do high speed video of tennis strokes using a Casio FH100. Your application is different.
Kinovea is an open source application for comparing videos, making measurements, etc. for sports or other applications. They have discussions on recording and comparing two cameras. Suggest that you look at the Kinovea forums. Also post there to find other researchers with experience.
Walking is pretty slow but I'd still look over my Kinovea thread on Basic High Speed Video Camera Considerations. Calculate motion between frames and motion blur for any camera that you are interested in. In particular, look at the information on indoor illumination and AUTO Exposure control. With AUTO control the exposure time (shutter speed) is usually unknown. If you are going to work indoors with the reduced illumination and your video camera only has AUTO exposure control there may be considerable motion blur depending on your required measurement accuracy.
The most advanced technology for your subject area can be found searching "motion capture".