DB Pullovers: anybody know how this move works?

Hey all! This is just a question regarding the DB Pullover that Kelli and Daniel do in their videos. From others I have heard that this more can lead to injury and is not safe for your shoulders but my question is how do you perform this move? Every time I do it, I don't really feel it and I think it's either because I'm not doing it right or not using enough weight. Any tips and suggestions would be great. Thank you