I watched the stream again and in fact, when Swen tried to catch the goblin, it showed a 65% chance. This means that it is definitely not 100%. In practice, it looks like there are at least 2 checks (one to catch and the other to hit another enemy).
A little testing would be nice. Unfortunately, only on Thursday I will be able to start it. I bet, however, that the enemies roll athletics or acrobatics (probably both, depending on what is higher)
As I wrote in the previous post, the enemies weight limits the effectiveness of the throw quite significantly, which means that if the character does not have a really high strength (20 is probably not enough to throw an average humanoid at a reasonable distance), it is unlikely that it would be worth wasting your action.
Importantly, "showing a 65% chance" does not actually mean there is a 65% to pick up and throw the enemy. That 65% chance could (and I argue, is) actually be showing the chance-to-hit that enemy with a thrown thing [whether object or creature]. It could be luck, but as I said elsewhere, none of the (4? 6?) throw attempts I saw failed. Only the actual hitting the target part ever failed.
Obviously more testing is warranted, and I
want throwing to have a chance to fail. I've just seen no evidence of that as of yet.