YouTube videos are not working when Elementor and Slider Revolution is installed
The root cause of the problem is a YouTube API conflict.
Revolution slider always uses the
https://www.youtube-nocookie.com domain to display their videos, which means we have to use the
https://www.youtube-nocookie.com domain as well, regardless of the YouTube And Vimeo Privacy Enhanced Mode option. (So even if you disabled the option, it will act as enabled to be able to stay compatible with Revolution Slider.) Otherwise our videos would not work, as YouTube does not allow using both
https://youtube.com/ on the same page to embed videos.
At Slider Revolution you can't change the YouTube privacy mode. At Smart Slider, it can be done at the Global Settings → General → YouTube And Vimeo Privacy Enhanced Mode option, which will make all videos created by Smart Slider use one URL. However, at Elementor you can change the
Privacy mode setting of the video at every single video widget. As a result, if you don't enable the
Privacy mode option when Slider Revolution is enabled, or when you turn on the
YouTube And Vimeo Privacy Enhanced Mode option of Smart Slider, one of the videos will not start
Make sure you turn on the
Privacy mode at your Elementor video widgets if Slider Revolution is installed on your site, or if you enabled the
YouTube And Vimeo Privacy Enhanced Mode at Smart Slider.