Who was the other person the colossal titan ate? At the beginning of episode 7 of season 2 (episode 32 on Crunchyroll), around 1:48, the colossal titan eats Ymir and one other person.


You can't see their face in any part of the episode.

Given who the colossal titan is, it seems strange to me that he would have eaten someone without a purpose, but only Ymir is seen later. 

Eventually, they run off on the armoured titans back and the second person is not with them.

Surely they could not have been digested in the short time the colossal titan was present, and they were swallowed whole. 

Later on, when we see them in human form in the giant forest, no one besides Eren and Ymir are with them. Do we know who this person was?
This was an unnamed, unlucky poor individual who was at the wrong place at the wrong time. If you watch this Youtube video, they aren't entirely sure who the Colossal Titan ate either.

It got Ymir!
...
And they got somebody else, too!

Also, while reading this reddit post, people say the Colossal Titan ate him to steal his ODM Gear

Just a random person. They didn't care about the guy, only about stealing his gear.

This is confirmed by seeing the Colossal Titan wearing the ODM gear in it's human form in the scene when they were camping out in the forest