This is one of many ways to approach splits and oversplits. It's also a helpful video to just target hamstring flexibility--you can skip the splits part if you like.
What's happening in splits?
This video emphasizes hamstrings more than hip flexors so feel free to add in hip flexor stretches if you feel the need.
Remember to approach your splits in a healthy fashion. Take your time, practice patience, respect your limits as you inquire into them, and enjoy your developing body awareness :)