After upgrade to 4.3, all the videos uploaded in posts are shown as links.

I have to edit the post and then inserted videos again with + button.

Then I save the post and videos embed correctly.

What do I have to do to make the old videos all embed?

Edit them, as you have found.

The new functionality isn't backwards compatible. I think you may have previously purchased my player plugin, which will provide that backwards compatibility.

Thank you @Nathan Explosion 

I thought that with this new function in IPS 4.3, and I didn´t need your plugin. But I was wrong.

Thanks!