This is how she did it:
1)Blunted razor blade against something.
2)get fake blood pack, and put liquid from it into her mouth.
3)just put razor on side of mouth behind molars.
4)swallow string
5)stop camera, tie razor to string, resume camera before she stoped it (whilst in same position) , whilst chewing
6)take it out and woila!
Me and my mate steve did a magic trick on vidio pohone, he mutated into me. I managed to get into hes exact same position, and because we had hidden our heads just before and after mutation it looked really cool. Pausing and resuming is oldest camera trick in world.