Before I start I just want to say I do like my MIL, so this isn't a total MIL bash

We usually talk to MIL and FIL via skype since they live interstate. DD is your typical almost 3 year old and wanders around chatting to them and easily gets distracted by other things while we do it. They love to chat to her and we encourage her to tell them things and try to keep her attention on the call.
MIL finds everything DD says is hilarious. Everything. Now sometimes DD does say funny things, words come out wrong, she says something cute and thinking that is funny is fine. But MIL cackles and tells FIL and whoever else is around 'DD is hilarious' every single time DD speaks. Yesterday DD said 'if I don't eat all my dinner, I don't get any jelly'. MIL laughed till she almost had tears. Now I don't think there is anything funny about that statement. It's just her repeating the rule in our house. DD was being serious when she said it, and she gave me a werid look when MIL laughed. Then I realised why it bugs me, it's like MIL is laughing AT DD. The way she repeats it to everyone it like DD is some kind of performing seal doing tricks to entertain her.
Now if I told her to stop laughing at my child I know she'd take it wrong so is there something I can say/do to let her know I don't like her laughing at my child?