I didn't watch "Storytellers," I listened to the song. I seriously don't think it's that cryptic. Take a look at the lyrics:
The "and" indicates that he's still in the same thought, which means that "that" refers to forgetting the way you feel right now.
Are you kidding? He lists at least six things he won't do.
He won't:
1. Forget the way you feel right now.
2. Forgive himself if you and he don’t go all the way tonight.
3. Do it better than he’ll do it with you. (For so long!)
4. Stop dreaming of you every night of his life.
5. Forget everything and move on.
6. Sooner or later be screwing around.
If Rolling Stone and their Gen X readers didn't spend all their time licking Cobain's rotting taint, at least three Nirvana songs would be on that list.
From what I've experienced with women with IUD (like Jauronimo, small sample size), you don't feel the IUD, but the string. I think it's possible for the IUD and string to move down a bit (the strings were just trimmed, right?).