Using these movements will help you to begin lengthening your hamstrings without stretching, if you take your time and work patiently. Since these are not stretches, please check yourself before you get to the end of your range of motion. Going to the end of your range of motion will not lengthen the hamstrings in any enduring way.
Research has demonstrated that movement, as opposed to stretching, is effective at lengthening the hamstrings without stretching.
Keep yourself comfortable and do less than you can. These movements can profitably be done on a regular basis. As the movements become more familiar, you’ll find that your hip and back flexibility also improve. Keep noticing any improvements, during and after your movement exploration, as that noticing will reinforce your new movement patterns.