Rajang kisses the glass window of the enclosure to try and smooch the mom's pregnant belly, possibly understanding very well that she has a baby growing in there. As adorable as this video is though, it's also kind of sad.
Rajang, who is almost 50 years old, is in a zoo, and therefore will never be able to make the connections he would be able to in the wild. Orangutans have proved themselves to be very smart, compassionate creatures, even in captivity, and knowing all of that makes this video a little more bittersweet.
Orangutans are very doting parents when they're in the wild, and they understand that sentiment just as strongly in captivity. Let's hope this sweet, caring orangutan is at least being treated well and kept as happy as possible.