Embedded YouTube videos not showing in Ckeditor in WordPress

Hi everybody

I installed and hooked the latest version of Ckeditor and use it in my WordPress comments system.

I found that WordPress blocked some tags such as img. Due to this issue, the images (inserted through URLs) were not added in the actual comments although images were displayed in Ckeditor before they were submitted (Please refer to this). I edited kses.php (under the /wp-includes/ folder) to include them and now it works fine except one issue:

When I embed a YouTube video in my comment, it’s displayed in Ckeditor. But it’s not displayed after I press the “Post Comment” button.

[youtube https://www.youtube.com/watch?v=8Jv47_VIBOQ

A broken YouTube link like above is displayed in the actual comment instead of displaying the YouTube video. I think it’s a similar issue (about inserting images) described above.

How can I fix this issue?

Thanks for your help.