There was a video with a pro-life person, I guess a protestant, who said that aborted babies go to Heaven. Then another person said that abortion must then be of a favour for these babies (since they go to Heaven).
I personaly am against abortion but I don't even know what to think about this. What would the Catholic response to this?
No one knows what happens to the souls of aborted babies. The Church doesn't have an answer. Saint Augustine believed that an unbaptized infant went to hell -- because that's what every human being actually deserves, and those who are baptized and cooperate with God's grace are saved. In the middle ages, the idea of Limbo came along -- a place of "natural happiness" where unbaptized babies and other unbaptized good people can spend eternity. When Vatican II came along, the official position of the Church was that God made it possible for every human being to be saved, and they would be saved through the life, death and resurrection of Jesus, whether or not they were Christian, even whether or not they believed in God. Salvation comes about because of cooperation with God's grace. Not everyone is given the gift of faith. The gift of faith is not just for the person who gets it, but is intended to make that person a disciple, who uses his/her gifts to bring about the kingdom of heaven. In other words, if I have the gift of faith and don't use it properly, I may be in more trouble than a good Buddhist, who didn't get the gift of faith but lives a blameless life. And finally, the Church says that all religions have something in them that is good, and that just shows that the Holy Spirit does whatever he wants. I know that's complicated, but it's sort of a summary. And the answer to your question is that a pre-born human being who cooperates with God's grace as best he/she can at that stage of life in all likelihood will go to heaven. I tell people who ask why we baptize infants that we presume that if the infant (who has had no life experience of signficance) could be asked whether he/she wanted to be adopted into God's family and given access to eternal salvation, the infant would say yes. But as you gain life experience and begin understanding what this really means you also gain the possibility of saying no, which is sin. So in that sense the unborn who are sinless desire baptism. By the way, you can show that this idea that everyone can be saved really goes back all the way to biblical times, so the Church isn't saying anything new, just putting it out as "official".
In sum, it is possible that each human being be saved. But I can't tell whether a particular human being is saved or not, even unborn ones. But I think, based on the above, that they are.