Final Cut Pro - Slow Motion Library

You're the first person I've ever heard of in over two decades who wants to slow down footage in the Browser, so this is really interesting to me. What is the reason for this? I'm sincerely curious.

In FCP, no, you can't do it in the Browser directly. But you can open a clip into its own timeline and do it. Just be sure to undo it or it'll be like that in every place you use it after that.

Select a clip in the Browser.

Go to the Clip menu.

Choose "Open Clip".

Now you'll see the clip's contents (audio and video) in its own timeline. Anything you do here, you're doing to the master clip, so it will carry over into any timeline you place a copy in. So undo whatever you do here, especially retiming, it'll screw you up later.

Good luck on your journey Fernando!

Another great resource are the Apple FCP docs: What is Final Cut Pro? - Apple Support

When you run into problems that you can't figure out, come back here for help. There are lots of very experienced FCP users here.

Yes, even in other NLEs I never select my slow motion footage that way. I know where the action needs to start and stop to be relevant/consistent with the overall scene. So I just make that a favorite and move on. Also, FCP's magnetic timeline allows you to experiment with slow motion in the timeline much easier, faster, and without screwing up anything already done, unlike other NLEs, so it was meant for you to do that experimenting in the timeline itself. And there's the opening the clip into its own timeline, as I mentioned in my previous post.

To really shorten the FCP learning curve I really recommend watching the free izzyvideo tutorials or for a modest amount, Mark and Steve at Ripple Training are excellent. Either of these would literally shave off days of the inevitable head-scratching. I came from the Avid and had some un-learning to do while wrapping my head around FCP's magnetic timeline, secondary storyline and roles. Once you get the mindset, it's amazingly fast and productive.

As a very long time Apple certified FCP trainer, first thing I always told my classes for FCPX, "forget everything you've ever learned about any NLE ever, including legacy FCP!"

macProVideo.com has great training, some of the best, plus the price gets you access to thousands of other trainings for other apps. Plus, Jenn Jager Pro Tutorials on YouTube are GREAT and free. I super highly recommend Iain Anderson's amazing book.

Then these:

https://www.youtube.com/playlist?list=PLE8oLb6vESxIruIVH1ZDOlXvrTd939Y3p

Another simple thing - in this case - is to press the K and L key together. This plays back in half speed - it's not 24 vs 60 but something which will give you an idea of ;-)