Stretching and flexibility is very important when training for speed. Speed requires ballistic movements and explosive power. To get your body ready for exercise you should always begin with warm-ups. Warm-ups can then be followed by some light static stretching. Static stretching should also be used post workout to help with the recovery process. If ever your body becomes too tight, add an extra stretching day throughout the week to help you recover more quickly.
Listed in the video is several range of motion exercises that can help get you loose. If you find that these exercises are too difficult, complete less range of motion. Flexibility training should not cause injury. Stay within your means, and work for more range of motion as your body is warmed up.
Please let us know if you have any questions or need help finding more flexibility and strength training drills.