There are plenty of videos of people detailing why they believe footage is fake. You can go look at that. Most of it comes down to sketchy details in footage. I've looked at such videos and some of it can be convincing, but not conclusive by any means. With regards to the moon, I think we just have a hard time intuiting how gravity will play out, so it's easy to make arguments that motion should look different than the videos shows. The only reference points are the ones they're 'debunking'.

I'll also note, NASA has absolutely been caught releasing fake/edited pictures/videos. That does not mean that moon landing was fake. Sometimes it's just convenient to take something from a training exercise, edit it, and release it as part of some promotional content.