For the second variation, do the same stretch with your feet together. This will increase the pressure on your hamstrings, so be careful. With all of these golfing exercises for flexibility and stretches you want to be very gentle and slow.
No bouncing to stretch further. Just stretch until you feel a good pull and hold it for a couple of seconds. And than release.
The more you do hamstring stretches the more flexible you will become in the end.