With Canon 5D Mark 3 Camera, I tried to shoot some video experiment but failed due to the same battery issue with this video. Since I realized the issue, I divided my experiment to two parts: one is trying different settings with photo shoots and the other is taking a video with iPhone to test speed.
A gummy bear and a plastic(?) dinosaur. Both room and oven lights were used and the oven door was almost always open. Both the gummy bear and the dinosaur melted quickly with low heat.
Three fish jellies. Both room light and oven light were on in the beginning but later only shot with the oven light. Also, took some shots outside of the oven. Didn't melt quickly and required high heat - it boiled rather than melting.
One ghost-shaped marshmallow. Similar with the fish jellies, it couldn't stand stable while melting and fell into flat side. Only oven light was used. The object's size was much more satisfying than the other two examples. The oven door was first closed in the beginning and opened in later parts.